Why are G-protein coupled receptors often known as 7TM receptors? A. They have 7 transmembrane β-pleated sheets. B. They have 7 transmembrane α-helices. C. They have 7 tyrosine-methionine dipeptides in their structure. D. They have 7 methionine-tryptophan dipeptides in their structure.

Answer: B

Explanation:

G protein-coupled receptors (GPCRs), also known as seven - (pass) - transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptor, and G protein-linked receptors (GPLR), comprises of a large protein family of receptors that discover molecules outside the cell and initiate internal signal transduction pathways and, eventually, cellular responses. They are called seven-transmembrane receptors because they pass through the cell membrane seven times