Question

Indicate true (T) and false (F) statements below regarding G-protein-coupled receptors (GPCRs). Your answer would be a five-letter string composed of letters T and F only, e.g. TTFF.

1. All GPCRs share a similar structure composed of seven transmembrane helices.
2. All GPCR ligands (signal molecules) have a similar structure.
3. The hormone insulin is recognized by a GPCR on the surface of its target cells.
4. Once activated, a GPCR molecule can activate multiple molecules of G protein to amplify the incoming signal.

Answer 1

GPCRs have seven transmembrane helices, but their ligands vary in structure. Insulin does not bind to a GPCR, but to a tyrosine kinase receptor. An activated GPCR can indeed activate multiple G proteins, amplifying the signal.

Step-by-step explanation:

The true (T) or false (F) statements regarding G-protein-coupled receptors (GPCRs) can be evaluated as follows:

• All GPCRs share a similar structure composed of seven transmembrane helices. - True
• All GPCR ligands (signal molecules) have a similar structure. - False
• The hormone insulin is recognized by a GPCR on the surface of its target cells. - False
• Once activated, a GPCR molecule can activate multiple molecules of G protein to amplify the incoming signal. - True

The correct five-letter string composed of letters T and F only is TTFT.