GPCR transmembrane feature

GPCR transmembrane feature

• A. 7 transmembrane regions
• B. 8 transmembrane regions
• C. 5 transmembrane regions
• D. 12 transmembrane regions

Answer: (A)

GPCRs are defined by a heptahelical, seven-pass transmembrane structure. This arrangement creates a compact bundle that forms the ligand-binding pocket within the transmembrane domain and leaves intracellular loops positioned to interact with G proteins. When a ligand binds, the receptor shifts conformation across these seven helices, enabling activation of the heterotrimeric G protein and signal transmission inside the cell. The seven-transmembrane design is consistent across classical GPCRs, making it the hallmark feature. Other transmembrane counts don’t fit this receptor class (for example, eight, five, or twelve would point to different families of membrane proteins).

GPCRs are defined by a heptahelical, seven-pass transmembrane structure. This arrangement creates a compact bundle that forms the ligand-binding pocket within the transmembrane domain and leaves intracellular loops positioned to interact with G proteins. When a ligand binds, the receptor shifts conformation across these seven helices, enabling activation of the heterotrimeric G protein and signal transmission inside the cell. The seven-transmembrane design is consistent across classical GPCRs, making it the hallmark feature. Other transmembrane counts don’t fit this receptor class (for example, eight, five, or twelve would point to different families of membrane proteins).