Pharmacodynamics

G Protein-Coupled Receptor GPCR

TRG Proteinine Kenetli Reseptör
Also known as:Seven-transmembrane receptor · 7TM receptor · Metabotropic receptor · Serpentine receptor

A member of the largest family of cell-surface receptors, a single polypeptide with seven transmembrane α-helices that transduces ligand binding into intracellular signals by activating heterotrimeric G proteins.

In depth

Agonist binding promotes GDP–GTP exchange on the Gα subunit, which dissociates from Gβγ; both then regulate effectors. Gs stimulates and Gi inhibits adenylyl cyclase (cAMP), Gq activates phospholipase C (IP3, DAG, Ca²⁺), and βγ subunits of Gi/o open GIRK potassium channels. Signalling ends when Gα hydrolyses GTP; receptors are then desensitised by GRK phosphorylation and β-arrestin binding.

GPCRs are the targets of about one-third of approved drugs, including those acting at adrenoceptors and at muscarinic, histamine, dopamine, serotonin, opioid, angiotensin II and GLP-1 receptors. Responses develop within seconds and are highly amplified.

Clinical pearl

The coupled G protein predicts effects: cardiac β1-receptors (Gs) raise cAMP and contractility, whereas M2 receptors (Gi) slow the heart rate, which is why atropine abolishes vagally mediated bradycardia.

Example drugs

Metoprolol Morphine Losartan Atropine Semaglutide
TRIn Turkish

G Proteinine Kenetli Reseptör

Yedi transmembran α-heliksten oluşan tek bir polipeptit zincirine sahip, ligand bağlanmasını heterotrimerik G proteinlerini aktive ederek hücre içi sinyallere dönüştüren ve hücre yüzeyi reseptörlerinin en büyük ailesini oluşturan reseptördür.

Agonist bağlanması Gα alt biriminde GDP–GTP değişimini başlatır; Gα, Gβγ'dan ayrılır ve her ikisi de efektörleri düzenler. Gs adenilil siklazı uyarır, Gi ise inhibe eder (cAMP); Gq fosfolipaz C'yi aktive eder (IP3, DAG, Ca²⁺); Gi/o'nun βγ alt birimleri ise GIRK potasyum kanallarını açar. Sinyal, Gα'nın GTP'yi hidrolize etmesiyle sonlanır; reseptörler ardından GRK aracılı fosforilasyon ve β-arrestin bağlanmasıyla desensitize olur.

GPCR'ler onaylı ilaçların yaklaşık üçte birinin hedefidir; adrenerjik, muskarinik, histamin, dopamin, serotonin, opioid, anjiyotensin II ve GLP-1 reseptörleri bunlar arasındadır. Yanıtlar saniyeler içinde gelişir ve güçlü biçimde amplifiye edilir.

Reseptörün kenetlendiği G proteini etkileri öngörmeye yardımcı olur: kalpteki β1 reseptörleri (Gs) cAMP düzeyini ve kasılma gücünü artırırken M2 reseptörleri (Gi) kalp hızını yavaşlatır; atropinin vagal kaynaklı bradikardiyi ortadan kaldırması bu nedenledir.

Diğer adları:G proteini kenetli reseptör · Yedi transmembran reseptör · Metabotropik reseptör
Updated 24.09.2026 1 views Educational reference — verify against current sources before clinical use.

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ReceptorReseptör

A macromolecule, usually a protein, to which a drug or endogenous ligand binds specifically and thereby initiates a change in cell function that produces a biological response.

 Second Messengerİkinci Haberci

A small intracellular signalling molecule or ion, such as cAMP, cGMP, IP3, diacylglycerol or Ca²⁺, whose concentration changes in response to receptor activation and which relays and amplifies the signal inside the cell.

 Ligand-Gated Ion ChannelLigand Kapılı İyon Kanalı

A transmembrane ion channel that opens (or, less often, closes) directly when a specific ligand, usually a neurotransmitter, binds to it, producing rapid changes in membrane potential within milliseconds.

 Receptor Down-RegulationReseptör Down-Regülasyonu

A decrease in the number of receptors available at the cell surface or in the cell, typically in response to prolonged or excessive agonist stimulation, which reduces tissue responsiveness.

 AgonistAgonist

A drug or endogenous substance that binds to a receptor and activates it, producing a biological response; it possesses both affinity and efficacy (intrinsic activity).

 Inverse AgonistTers Agonist

A ligand that binds to a receptor with constitutive (ligand-independent) activity and reduces that basal activity, producing an effect opposite in direction to that of an agonist.