Final answer:
A GTPase is a protein that hydrolyzes GTP into GDP, and Rab proteins are an example of GTPases that regulate vesicle trafficking. GEF proteins activate Rab proteins by facilitating GTP binding, while GAP proteins inactivate Rab proteins by promoting GTP hydrolysis.
Step-by-step explanation:
A GTPase is a protein that hydrolyzes GTP into GDP, using the energy released to carry out cellular processes. Rab proteins are a type of GTPase that regulate vesicle trafficking in cells. They function by cycling between an active GTP-bound state and an inactive GDP-bound state.
GEF (Guanine Exchange Factor) proteins facilitate the exchange of GDP for GTP on Rab proteins, activating them. GAP (GTPase Activating Protein) proteins promote the hydrolysis of GTP into GDP on Rab proteins, inactivating them.