What is a notable feature of GPCRs?

What is a notable feature of GPCRs?

• A. They feature 7 transmembrane regions connected to a G-protein with alpha, beta, and gamma subunits
• B. They form tight junctions between cells
• C. They are lipids that act as hormones
• D. They are soluble cytosolic enzymes

Answer: (A)

GPCRs are defined by seven transmembrane segments that span the cell membrane and couple to a heterotrimeric G protein made of alpha, beta, and gamma subunits. When a ligand binds, the receptor changes shape and promotes GDP to GTP exchange on the alpha subunit. The activated Gα–GTP and the freed Gβγ dimer then regulate downstream effectors like adenylyl cyclase and phospholipase C, producing second messengers such as cAMP, IP3, DAG, and calcium. This combination of the seven-helix membrane structure and direct coupling to a heterotrimeric G protein is what defines GPCRs and sets them apart from other protein types, such as those forming tight junctions, lipid-derived hormones that act without a membrane receptor, or soluble cytosolic enzymes.

GPCRs are defined by seven transmembrane segments that span the cell membrane and couple to a heterotrimeric G protein made of alpha, beta, and gamma subunits. When a ligand binds, the receptor changes shape and promotes GDP to GTP exchange on the alpha subunit. The activated Gα–GTP and the freed Gβγ dimer then regulate downstream effectors like adenylyl cyclase and phospholipase C, producing second messengers such as cAMP, IP3, DAG, and calcium. This combination of the seven-helix membrane structure and direct coupling to a heterotrimeric G protein is what defines GPCRs and sets them apart from other protein types, such as those forming tight junctions, lipid-derived hormones that act without a membrane receptor, or soluble cytosolic enzymes.