B. (3pts) Imagine that the ARF1 GTPase protein was mutated so that it could not
ID: 256374 • Letter: B
Question
B. (3pts) Imagine that the ARF1 GTPase protein was mutated so that it could not hydrolyze UP, regardless of its binding partners. Would you expect ARF1-initiated transport vesicles to bud off normally? How might subsequent or downstream steps in transport be affected it ARF1 cannot hydrolyze GTP into GDP? C. (3pts) What if the ARF1 protein was mutated so that it was locked in a GDP-bound state, regardless of its binding partners. How would you expect this mutation to affect transport vesicle coat formation? D. (2pts) GTPase. Additionally, please predict which type of motor protein is most likely involved in vesicle transport to these destinations. lease identify two plausible cellular destinations of vesicles associated with ARF1Explanation / Answer
Ans B. When the ARF1 cofactor is in active form that is with GTP it allows formation of coat I proteins loaded vesicles which function in transport of lipids from golgi complexes to endoplasmic reticulum.After the task is completed that GTPase protein comes into picture which hydrolyses the GTP which is bound to the ARF,making it inactive. So according to this comcept if the GTPase is mutated then there will be budding of vesicles as this mutation does not interfere in budding process.
C IF the ARF is locked in GDP bound state, that is in inactive form then the N terminal alpha helix of ARF 1 cannot extrude from its hydrophobic pocket to assemble to the target organelle.Extrusion of Helix is brought about by association of GTP in place of GDP by Guanidine nucleotide exchanging factor(GEF) proteins.Thus GTP cannot get replaced by GDP.So there will be no transport through vesicles and there will be no coat protein formation.
D.Endoplasmic reticulum and plasma membrane are the destinations.
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