G protein-coupled receptors are important molecules involved in signal transduction.

Which statement about G protein-coupled receptors is true?

A. They are activated only by steroid hormones.

B. They bind both adenine and guanine nucleotides.

C. They generally contain seven membrane-spanning α helices.

D. They bind only guanine nucleotides.

Question

Kendall Duffy

Biology

15 February, 15:35

G protein-coupled receptors are important molecules involved in signal transduction.

Which statement about G protein-coupled receptors is true?

A. They are activated only by steroid hormones.

B. They bind both adenine and guanine nucleotides.

C. They generally contain seven membrane-spanning α helices.

D. They bind only guanine nucleotides.

+4

Answers (1)

Know the Answer?

Selina Shelton · Answer 1

C. They generally contain seven membrane-spanning α helices.

Explanation:

The G protein-coupled receptors are components of signal transduction through G protein. Here, a plasma membrane receptor with seven transmembrane helical segments serves as a G-protein coupled receptor. These receptors are the integral membrane proteins and have seven hydrophobic regions of 20 to 28 amino acid residues.

These hydrophobic alpha-helices span the membrane back and forth seven times. Binding of a signaling molecule to the G-protein coupled receptor promoters a conformational change in the receptor's intracellular domain. The activated receptor then triggers the replacement of bound GDP to the G protein by GTP and thereby activating it.