Question

Which type of cell-surface receptor undergoes changes in phosphorylation in response to binding of its ligand?A)G protein–coupled receptorB)receptor kinaseC)ligand-gated ion channelD)both the G protein–coupled receptor and the receptor kinase

Answer 1

Receptor kinases undergo changes in phosphorylation upon ligand binding, whereas G protein–coupled receptors activate G-proteins without direct phosphorylation.

Step-by-step explanation:

The type of cell-surface receptor that undergoes changes in phosphorylation in response to binding of its ligand is the receptor kinase. This receptor, specifically receptor tyrosine kinase, is characterized by its ability to autophosphorylate on tyrosine residues in response to ligand binding. The process involves pairs of receptors adding phosphate groups to each other which then triggers a pathway of cellular responses.

In contrast, the G protein–coupled receptor operates differently: upon ligand binding, it activates a G-protein, which then interacts with other proteins or enzymes, but it does not itself undergo phosphorylation.

Answer 2

Letter A. G-protein coupled receptor

Step-by-step explanation:

G protein-coupled receptors are a large protein family of transmembrane receptors that pick up extracellular signals and activate signal transduction pathways within the cell. They start this transduction through a chain of events triggered by phosphorylation.

In this question, we may be confused by the options that involve protein kinase, but we have to consider only cell surface receptors, as the request in question.