Biological signaling cascades depend upon fine-tuned molecular switches that continuously integrate environmental and chemical cues. While classical pharmacology long focused on orthosteric ligands that occupy the direct, evolutionarily conserved active sites of macromolecular targets, modern molecular sciences have embraced allosteric modulation as a far more nuanced, versatile, and structurally widespread regulatory paradigm. By acting at spatially discrete, topologically distinct binding sites, allosteric modulators alter macromolecular conformational equilibria, reshaping how proteins respond to their endogenous partners without overriding innate physiological rhythms.
Allosteric Modulation
1. Concise Definition
Allosteric modulation refers to the biological and pharmacological process whereby the binding of a molecule (an allosteric ligand or modulator) to a regulatory site—topographically distinct from the endogenous or active site—induces a conformational change in the macromolecule, thereby altering its binding affinity, signaling efficacy, or functional dynamics toward its primary (orthosteric) ligand.
In standard receptor pharmacology and enzymology, this phenomenon does not require direct competitive occupancy of the catalytic or native transmitter-binding pocket. Instead, the modulator acts non-covalently or covalently at an alternate domain, shifting the target protein’s structural ensemble between active, inactive, or intermediate states. Consequently, allosteric modulation can either augment, attenuate, or neutrally tune biological responses in an activity-dependent, temporally preserved manner.
Importantly, because allosteric modulators exert their effects cooperatively with endogenous biological signaling, their regulatory capacity possesses intrinsic saturability, often designated as a “ceiling effect.” This stands in stark functional contrast to orthosteric agonists or antagonists, which typically force linear, unconstrained activation or blockade that can precipitate dramatic off-target toxicity or profound homeostatic disruption.
2. Etymology & Linguistic Origin
The term allosteric derives from the Classical Greek roots allos (ἄλλος), meaning “other,” “different,” or “divergent,” and stereos (στερεός), denoting “solid,” “space,” or “three-dimensional body.” Combined with the suffix -ic, the neologism translates literally into “pertaining to another space” or “operating through a distinct spatial configuration.” The companion term modulation originates from the Latin modulatio (a rhythmic measure, regularized regulation), stemming from the verb modulari (“to measure out, regulate, or attune”), which itself traces back to modus (“measure, manner, or limit”).
The conceptual framework and linguistic coinage of “allostery” were introduced to the scientific canon in the early 1960s by the French molecular biologists Jacques Monod, François Jacob, and Jean-Pierre Changeux. While investigating non-overlapping feedback inhibition in bacterial metabolic enzymes such as L-threonine deaminase, they observed that end-product inhibitors lacked any chemical or structural homology with the enzyme’s primary substrates. To explain how an unrelated chemical entity could selectively curb enzymatic output without sterically impeding substrate access, Monod and Jacob formally introduced the adjective “allosteric” at the 1961 Cold Spring Harbor Symposium on Quantitative Biology. The concept quickly expanded from bacterial metabolic regulation to multimeric oxygen transport and, ultimately, to cellular receptor pharmacology and neurobiology.
3. Pronunciation & Grammatical Form
Phonetic Pronunciation:
- British English: /ˌæləˈstɪərɪk ˌmɒdjʊˈleɪʃən/
- American English: /ˌæləˈstɛrɪk ˌmɑːdʒəˈleɪʃən/
Grammatical Classifications:
- Allosteric modulation serves as a compound abstract noun phrase.
- Allosteric functions as a relational adjective modifying nouns such as site, modulator, interaction, regulation, transition, or effect.
- Modulate operates as the transitive verb indicating the action of inducing allosteric conformational shifts (e.g., “the therapeutic compound allosterically modulates synaptic transmission”).
- Allostery (/ˈæləstɪri/) represents the overarching uncountable noun encompassing the broader phenomenon or thermodynamic property.
- Modulator acts as the agent noun denoting the specific chemical entity, ion, or molecular ligand exerting the allosteric influence.
4. Detailed Conceptual Explanation
At the core of allosteric modulation lies the biophysical principle of thermodynamic coupling between non-overlapping spatial domains within a macromolecule. Rather than functioning as static, rigid architectures, proteins exist as dynamic conformational ensembles that populate multiple energy minima along a complex free-energy landscape. In the unliganded (apo) condition, a receptor or enzyme samples both inactive (ground) and active (signaling-competent) conformations, with equilibrium typically favoring the lowest-energy baseline state. When an allosteric ligand selectively recognizes and stabilizes a particular sub-state, it shifts this statistical equilibrium, fundamentally modifying the thermodynamic barrier required for the orthosteric ligand to bind or evoke a functional response.
This molecular dialog is defined by the cooperativity factor, traditionally symbolized by the Greek letter alpha (α) for binding affinity and beta (β) for signaling efficacy. When an allosteric modulator binds to its allosteric site simultaneously with an orthosteric agonist at its native pocket, the ternary complex (modulator-receptor-agonist) exhibits altered biophysical properties. If the modulator enhances the affinity of the orthosteric partner ($lpha > 1$), the interaction manifests positive cooperativity. Conversely, if the modulator destabilizes orthosteric binding ($lpha < 1$, but$> 0$), the interaction exhibits negative cooperativity. If the modulator exhibits no effect on affinity ($lpha = 1$) but augments or silences the signaling output triggered by the agonist ($eta > 1$ or $eta < 1$), it modulates operational efficacy.
A vital conceptual boundary separates allosteric modulation from uncompetitive and non-competitive enzyme inhibition, as well as simple steric hindrance. True allostery is defined by energetic communication across space—a long-range allosteric network of amino acid residues transmitting mechanical perturbations throughout the tertiary or quaternary protein matrix. Because the allosteric modulator occupies a separate binding pocket, it can remain bound concurrently with the orthosteric ligand without displacing it, enabling subtle, context-sensitive tuning of native physiological pathways.
Furthermore, allosteric modulators maintain intrinsic ceiling effects. Once the allosteric binding pocket approaches complete saturation, no additional allosteric conformational shift can be extracted, irrespective of escalating drug concentrations. This asymptotic limit distinguishes allosteric regulators from orthosteric compounds, which can continuously depress baseline signaling toward absolute cellular silencing or provoke maximal, potentially toxic activation. Consequently, allosteric modulation serves as an evolutionarily optimized buffer against biochemical extremes.
5. Historical Development
The foundations of allosteric theory originated in early twentieth-century biophysics, long before the term itself existed. In 1904, Christian Bohr documented the sigmoidal oxygen binding curve of hemoglobin and the cooperative displacement triggered by carbon dioxide and hydrogen ions (the Bohr effect). Later, in 1925, Gilbert Smithson Adair established that hemoglobin is a tetrameric protein exhibiting cooperativity: oxygen occupancy at one heme subunit increases the oxygen affinity of remaining vacant subunits.
The formal theoretical breakthrough occurred during the mid-twentieth century within metabolic biochemistry. Jacques Monod, Jean-Pierre Changeux, and François Jacob, working at the Institut Pasteur in Paris, noticed that the regulatory interactions governing bacterial feedback inhibition could not be accommodated by traditional competitive enzyme kinetics. In their historic 1963 and 1965 publications, Monod, Jeffries Wyman, and Changeux synthesized these empirical observations into the landmark Monod-Wyman-Changeux model (MWC model), establishing concerted symmetry transitions in multi-subunit complexes as a fundamental paradigm of biology. Concurrently, Daniel Koshland, George Némethy, and David Filmer (1966) posited an alternative, sequential induced-fit model (KNF model), emphasizing that subunit conformations change stepwise upon ligand binding.
By the late 1970s and 1980s, allostery migrated from multimeric enzymes into neuropharmacology. Landmark discoveries revealed that GABA_A receptors in the central nervous system possess distinct binding loci for benzodiazepines, barbiturates, and neurosteroids that allosterically potentiate inhibitory chloride currents initiated by gamma-aminobutyric acid (GABA). Research spearheaded by Claus Braestrup, Hanns Möhler, and Richard Olsen confirmed that clinically vital anxiolytics operated not as direct neurotransmitter mimetics, but as positive allosteric modulators.
The twenty-first century has witnessed an explosion of allosteric drug discovery across monomeric proteins, particularly G protein-coupled receptors (GPCRs), protein kinases, and receptor tyrosine kinases. Pioneering theoretical formulations by Arthur Christopoulos, Terry Kenakin, and Frederick Ehlert successfully integrated operational models of allosterism into pharmacology, while breakthroughs in cryogenic electron microscopy have visually confirmed atomic-resolution allosteric binding pockets across diverse receptor superfamilies.
6. Theoretical Foundations
The understanding of allostery is underpinned by three foundational biophysical and mathematical frameworks: the Monod-Wyman-Changeux (MWC) concerted model, the Koshland-Némethy-Filmer (KNF) sequential model, and modern dynamic energy landscape theory.
The MWC model postulates that an allosteric protein is an oligomer composed of identical, symmetrically arranged subunits. The entire multimer exists in pre-existing thermodynamic equilibrium between at least two distinct states: the tense (T) state, which exhibits low affinity for the primary substrate/agonist, and the relaxed (R) state, which possesses high affinity. In this paradigm, all subunits undergo simultaneous, concerted structural transitions, preserving structural symmetry. Allosteric activators shift the basal equilibrium toward the R state, whereas allosteric inhibitors trap the macromolecule in the T state.
Conversely, the KNF model rejects absolute symmetry conservation, advancing an induced-fit hypothesis. Ligand binding directly induces a conformational rearrangement in the specific subunit it contacts, which sequentially alters inter-subunit contact residues and progressively modulates the ligand affinity of adjacent, unliganded protomers. This model accommodates negative cooperativity—a structural outcome where initial ligand binding reduces the affinity of subsequent binding events—which cannot be readily explained by the classical MWC framework.
Contemporary biophysics has integrated these deterministic formulations into dynamic energy landscape theory. In this modern view, allosteric proteins are not restricted to two rigid states; rather, they exist as fluctuating conformational ensembles across multidimensional free-energy surfaces. Allosteric ligands remodel the topography of this energy landscape, lowering energetic barriers between specific functional microstates and selectively redistributing conformational populations. Consequently, allosteric modulation can occur not only through dramatic structural shifts (quaternary reorientations), but also purely via changes in structural dynamics and vibrational entropy—a phenomenon termed dynamic allostery.
7. Key Components, Types & Dimensions
Allosteric modulators are categorized according to their functional consequences on orthosteric ligand binding, downstream signaling efficacy, and intrinsic agonist capability. The formal classification endorsed by the International Union of Basic and Clinical Pharmacology includes:
- Positive Allosteric Modulators (PAMs): Ligands that bind to an allosteric site and simultaneously enhance the affinity ($lpha > 1$), signaling efficacy ($eta > 1$), or both ($lphaeta > 1$) of the orthosteric agonist. In the absence of the endogenous agonist, pure PAMs produce negligible or undetectable receptor activation, functioning strictly as physiological amplifiers.
- Negative Allosteric Modulators (NAMs): Ligands that bind allosterically to reduce the affinity ($lpha < 1$) or efficacy ($eta < 1$) of the orthosteric agonist. NAMs act as non-competitive biological brakes, dampening hyperactive signaling without completely obliterating endogenous baseline signaling if designed with modest negative cooperativity.
- Silent Allosteric Modulators (SAMs) / Neutral Allosteric Ligands (NALs): Compounds that bind with high affinity to an allosteric pocket without significantly altering orthosteric binding affinity or signaling efficacy ($lpha pprox 1, eta pprox 1$). While physiologically silent on their own, SAMs competitively displace PAMs or NAMs from the allosteric locus, serving as valuable pharmacologic decoys or therapeutic antidotes against allosteric toxicity.
- Allosteric Agonists (Ago-PAMs): Bifunctional modulators that possess intrinsic signaling capacity in the complete absence of an endogenous orthosteric ligand, while concurrently acting as positive allosteric modulators when the native ligand is present.
- Bitopic / Dualsteric Ligands: Engineered bivalent molecules containing two pharmacophores covalently linked through an optimized spacer arm. One moiety docks within the orthosteric pocket to guarantee signaling engagement, while the secondary domain binds an adjacent allosteric vestibule, conferring exceptional subtype selectivity.
8. Examples & Illustrative Cases
Numerous clinically successful pharmacotherapies and endogenous metabolic networks demonstrate the versatility of allosteric regulation across various biological substrates:
1. The GABA_A Receptor and Benzodiazepines: One of the most famous examples of allosteric modulation occurs at the pentameric GABA_A receptor complex. The endogenous neurotransmitter GABA binds at the interface of the alpha and beta subunits ($lpha/eta$), opening the central pore to allow chloride influx and induce cellular hyperpolarization. Benzodiazepines (e.g., diazepam, lorazepam) bind to a distinct regulatory pocket at the alpha and gamma ($lpha/\gamma$) subunit interface. Benzodiazepines cannot open the chloride channel independently; instead, they act as PAMs, increasing the channel’s opening frequency in response to GABA, thereby mediating sedative, hypnotic, anxiolytic, and anticonvulsant effects with a vastly superior safety profile compared to older, orthosteric GABAergic channel openers.
2. The Calcium-Sensing Receptor (CaSR) and Cinacalcet: The calcium-sensing receptor is a class C GPCR located on parathyroid cells that governs systemic calcium balance. Cinacalcet is an FDA-approved positive allosteric modulator that docks into the transmembrane bundle of CaSR. By amplifying the receptor’s sensitivity to extracellular calcium ions, cinacalcet drives sustained suppression of parathyroid hormone secretion without requiring supra-physiological serum calcium concentrations, providing targeted therapy for secondary hyperparathyroidism.
3. NMDA Receptor Regulation: The ionotropic N-methyl-D-aspartate (NMDA) receptor showcases obligate multi-site allosteric interplay. Channel activation requires the concurrent binding of glutamate to the GluN2 subunit and glycine to the GluN1 subunit. In addition, ambient extracellular magnesium ($Mg^{2+}$) acts as a voltage-dependent allosteric blocker within the pore, zinc ($Zn^{2+}$) binds amino-terminal domains to exert negative allosteric modulation, and neurosteroids bind transmembrane interfaces to provide positive or negative allosteric tone depending on their structural polarity.
9. Measurement & Assessment
Evaluating allosteric modulation requires quantitative pharmacology techniques capable of resolving interactions between multiple binding partners acting simultaneously on a single protein target.
Radioligand Binding Assays: Equilibrium binding assays track how increasing concentrations of an allosteric modulator displace or augment the binding of a fixed concentration of labeled orthosteric radioligand. Unlike competitive orthosteric displacement, which yields steep curves that completely displace radioligand binding to zero baseline, allosteric curves plateau at an asymptotic, partial level of inhibition or enhancement. Equilibrium binding models fit these curves using the Allosteric Ternary Complex Model, calculating the binding affinity of the modulator for the free receptor ($K_B$) and the cooperativity factor ($lpha$).
Kinetic Dissociation Assays: A definitive empirical signature of allostery is the alteration of orthosteric ligand dissociation kinetics. In an infinite dilution paradigm, an orthosteric competitor cannot modify the rate at which a bound radioligand dissociates from its target. However, if an allosteric modulator is introduced during dissociation, it binds its distinct pocket, alters the receptor’s conformation, and directly accelerates or decelerates the dissociation rate of the orthosteric ligand. Measuring dissociation kinetics is therefore widely considered the gold standard for verifying that a ligand’s mechanism of action is non-orthosteric.
Functional Biosensors and Second-Messenger Readouts: Downstream cellular consequences are tracked through real-time assays, including Förster/Bioluminescence Resonance Energy Transfer (FRET/BRET) biosensors, cyclic adenosine monophosphate (cAMP) accumulation, and intracellular calcium mobilization. Mathematical deconvolution using the Operational Model of Allosterism allows investigators to decouple binding cooperativity ($lpha$) from functional efficacy modulation ($eta$), ensuring accurate drug profiling.
10. Applications & Practical Significance
Allosteric modulation holds tremendous practical significance for rational drug discovery and clinical therapeutics, particularly in targets where traditional orthosteric pharmacology has reached translational bottlenecks.
Subtype Selectivity in Conserved Protein Families: Orthosteric binding sites of closely related receptor families often share near-identical amino acid sequences because they must bind the same endogenous neurotransmitter or metabolite. For instance, the orthosteric pockets of muscarinic acetylcholine receptors (M1 through M5) are virtually identical, causing classical orthosteric agonists to provoke severe cholinergic side effects (such as cardiac arrhythmia and gastrointestinal distress). In contrast, allosteric binding sites located within exterior vestibules or deep transmembrane crevices are subject to far less evolutionary pressure, exhibiting significant sequence divergence. Consequently, medicinal chemists can synthesize highly selective allosteric modulators—such as selective M1 or M4 PAMs for schizophrenia and Alzheimer’s disease—that avoid off-target toxicities.
Preservation of Spatiotemporal Signaling: Classical agonists flood physiological systems indiscriminately, overriding natural, event-driven signaling cascades. In neural tissue, this constant stimulation can cause receptor desensitization, downregulation, structural internalizations, and profound tolerance. PAMs, by contrast, are functionally silent during quiescent phases and only amplify signaling precisely when and where endogenous neurotransmitters are transiently released into the synaptic cleft. This preservation of spatiotemporal fidelity reduces receptor desensitization and enhances therapeutic tolerance over long treatment courses.
Enhanced Therapeutic Index and Saturability: Because the magnitude of an allosteric modulator’s effect is fundamentally limited by its cooperativity factor ($lpha$ and $eta$), escalating drug exposures encounter a therapeutic plateau. This saturability prevents life-threatening drug overdoses, providing an intrinsically wider therapeutic margin compared to orthosteric modulators.
11. Research & Empirical Evidence
Extensive structural and empirical investigations over the past two decades have consolidated allostery from a theoretical model into an observable physical reality.
Seminal investigations by Christopoulos and Kenakin demonstrated that allosterism is structurally ubiquitous throughout all four major classes of GPCRs. Using operational models, their research revealed that allosteric sites frequently exhibit probe dependence: an allosteric modulator does not uniformly alter all orthosteric agonists by the exact same cooperativity factor. Instead, the magnitude and even direction of cooperativity depend on the chemical structure of the orthosteric partner, demonstrating that protein conformational ensembles are multifaceted and ligand-specific.
Structural breakthroughs driven by X-ray crystallography and cryogenic electron microscopy have provided atomic-level snapshots of these transitions. Landmark studies led by Brian Kobilka, Robert Lefkowitz, and colleagues resolved GPCRs bound simultaneously to orthosteric agonists, intracellular G proteins, and positive or negative allosteric modulators. For example, high-resolution structures of the beta-2 adrenergic receptor and chemokine receptors demonstrated how allosteric ligands dock into lipid-facing, intracellular, or extracellular vestibules, physically freezing or loosening specific micro-switches to modulate downstream heterotrimeric G protein and beta-arrestin recruitment.
In central nervous system pharmacology, research led by P. Jeffrey Conn and colleagues at the Vanderbilt Center for Neuroscience Drug Discovery has validated metabotropic glutamate receptor (mGluR) allosteric modulators in animal models of neuropsychiatric disease. Their work confirmed that selectively targeting allosteric pockets on mGluR4, mGluR5, or muscarinic receptors rescues cognitive and behavioral phenotypes without generating the rapid tolerance, motor deficits, or seizures seen with direct orthosteric agents.
12. Cultural & Cross-Cultural Considerations
While the basic biophysical mechanisms of allosteric modulation are universal across human physiology, several key factors shape the cross-cultural and international development of allosteric drugs:
Pharmacogenomics and Structural Polymorphisms: Genetic diversity across human populations influences drug-receptor interactions. Because allosteric binding pockets face less evolutionary selection pressure than orthosteric pockets, they display higher rates of non-synonymous single nucleotide polymorphisms (SNPs) across diverse ancestral cohorts. A silent mutation in an allosteric pocket that does not affect native neurotransmitter function may dramatically alter the affinity or cooperativity of an allosteric drug. Consequently, multinational clinical trials must carefully evaluate allosteric drug responses across genetically diverse populations to account for pharmacogenomic variability.
Global Regulatory and Nomenclature Standards: Historically, distinct national regulatory bodies struggled to categorize allosteric candidates within standard pharmacological frameworks. Today, global standards coordinated by the International Union of Basic and Clinical Pharmacology (IUPHAR) and the World Health Organization (WHO) provide clear guidelines for classifying allosteric drugs, ensuring consistent safety metrics and regulatory definitions across jurisdictions.
Healthcare Equity and Modern Allosteric Therapeutics: Designing allosteric modulators typically requires high-throughput screening, cryo-EM structural biology, and advanced computational chemistry. Because these proprietary candidates are complex and expensive to develop, initial access to new allosteric drugs is often concentrated in high-income healthcare systems. Expanding global health partnerships is critical to ensuring that breakthroughs in allosteric therapies for conditions like tuberculosis, infectious diseases, and treatment-resistant neuropsychiatric disorders are distributed equitably worldwide.
13. Criticisms, Debates & Limitations
Despite their clear pharmacological advantages, allosteric modulators present unique theoretical and translational challenges:
The Challenge of Probe Dependence: An allosteric drug developed using an artificial radioligand or synthetic surrogate agonist may display entirely different cooperativity when paired with the native endogenous neurotransmitter. This probe-dependent effect can yield misleading preclinical screens, requiring early and careful validation against native biological ligands in physiologically relevant cellular environments.
Biased Allosteric Modulation: Receptor activation triggers multiple diverging downstream pathways, such as G-protein coupling versus beta-arrestin recruitment. Allosteric modulators can selectively enhance one pathway while simultaneously inhibiting another—a phenomenon termed pathway-biased allosteric modulation. While this bias provides unique therapeutic opportunities, it also introduces pharmacological complexity that makes it difficult to predict comprehensive phenotypic outcomes in human trials.
Steep Structure-Activity Relationship (SAR) Cliffs: Because allosteric pockets are often shallow, flexible, or lipid-exposed, minor chemical modifications can unexpectedly abolish allosteric affinity or flip a compound’s functional activity from positive cooperativity (PAM) to negative cooperativity (NAM). This structural sensitivity makes lead optimization challenging for medicinal chemists, often complicating the translation of initial hit compounds into stable clinical candidates.
Dependence on Endogenous Tone: Pure allosteric modulators require the presence of native endogenous ligands to exert their downstream effects. In end-stage neurodegenerative diseases where presynaptic neurons have degenerated and native neurotransmitter release is exhausted, a PAM may lose its therapeutic utility entirely unless co-administered with an orthosteric precursor or agonist.
14. Related Terms & Distinctions
To prevent conceptual confusion, allosteric modulation must be clearly distinguished from related pharmacological phenomena:
- Orthosteric Agonism vs. Allosteric Modulation: Orthosteric agonists bind directly to the primary, evolutionarily selected active site, stimulating receptor activity in a concentration-dependent manner regardless of endogenous signaling. Allosteric modulators bind distinct non-catalytic pockets, acting conditionally to adjust the target’s sensitivity to orthosteric ligands.
- Competitive Antagonism vs. Negative Allosteric Modulation (NAM): Competitive antagonists directly occupy the orthosteric site, physically blocking agonist access; their inhibitory effect can be overcome by surmounting concentrations of the agonist (surmountable antagonism, causing a rightward parallel curve shift). In contrast, NAMs bind an alternate locus and change receptor conformation, often depressing the maximal possible response (insurmountable blockade) with an intrinsic saturable ceiling.
- Uncompetitive Inhibition vs. Allosteric Modulation: Uncompetitive inhibitors are a subtype of enzyme inhibitors that bind strictly to the pre-formed enzyme-substrate complex, but cannot bind the free enzyme alone. True allosteric modulators typically bind both the unliganded macromolecule and the ligand-bound intermediate, shifting the thermodynamic equilibria between these states.
- Biased Agonism vs. Allosteric Modulation: Biased agonism (functional selectivity) occurs when an orthosteric or allosteric ligand preferentially drives one downstream signaling cascade over another. While allosteric modulators can exhibit biased allosteric modulation, the two terms are not synonymous; allosterism refers to the physical site of binding, whereas bias describes divergent signaling pathway selection.
15. Summary / Key Takeaways
Allosteric modulation represents a foundational pillar of biophysics and targeted drug design. By targeting non-orthosteric binding pockets across multi-subunit complexes and monomeric receptors, allosteric modulators reshape the conformational energy landscapes of their macromolecular targets. This regulatory approach offers key therapeutic advantages, including high receptor subtype selectivity, the preservation of native spatiotemporal signaling patterns, and an intrinsic ceiling effect that mitigates toxicity.
From early twentieth-century insights into hemoglobin cooperativity to modern cryo-EM structural biology and allosteric drug discovery, the field continues to transform our understanding of cell signaling. Despite practical hurdles such as probe dependence, steep SAR cliffs, and pathway-selective bias, allosteric pharmacology remains a promising frontier for developing safer, more precise therapeutics for complex neurological, metabolic, and systemic disorders.
References
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- Christopoulos, A. (2002). Allosteric binding sites on cell-surface receptors: Novel targets for drug discovery. Nature Reviews Drug Discovery, 1(3), 198–210. https://doi.org/10.1038/nrd746
- Kenakin, T. (2017). A Pharmacology Primer: Techniques for More Effective and Strategic Drug Discovery (5th ed.). Academic Press.
- Monod, J., Wyman, J., & Changeux, J. P. (1965). On the nature of allosteric transitions: A plausible model. Journal of Molecular Biology, 12(1), 88–118. https://doi.org/10.1016/S0022-2836(65)80285-6
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