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. TTFFF.
( ) All GPCRs share a similar structure composed of seven transmembrane helices.
( ) All GPCR ligands (signal molecules) have a similar structure.
( ) GPCRs have only been found in multicellular organisms, consistent with their role in intercellular signaling.
( ) The hormone insulin is recognized by a GPCR on the surface of its target cells.
( ) Once activated, a GPCR molecule can activate multiple molecules of G protein to amplify the incoming signal.

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. TTFFF.
( )	All GPCRs share a similar structure composed of seven transmembrane helices.
( )	All GPCR ligands (signal molecules) have a similar structure.
( )	GPCRs have only been found in multicellular organisms, consistent with their role in intercellular signaling.
( )	The hormone insulin is recognized by a GPCR on the surface of its target cells.
( )	Once activated, a GPCR molecule can activate multiple molecules of G protein to amplify the incoming signal.

Quizplus · Accepted Answer

All GPCRs (found in multicellular as well as unicellular organisms) belong to a large family of proteins that share a similar structure with seven transmembrane helices. Despite this similarity, they recognize a wide variety of ligands. The GPCR activates the ? subunit of a trimeric G protein, which is then released; this is usually followed by the binding of another ? subunit to repeat the cycle for as long as the receptor is activated. Insulin is recognized by a receptor tyrosine kinase.

Indicate True (T) and False (F) Statements Below Regarding G-Protein-Coupled