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3 A) Which of the following statements regarding signal sequences is NOT true? T

ID: 219876 • Letter: 3

Question

3 A) Which of the following statements regarding signal sequences is NOT true?

The di-arginine sorting sequence can be located anywhere in the cytoplasmic domain of an ER-resident protein.

A protein with a KDEL sequence localizes to the ER via COPI retrieval.

The KDEL receptor contains a C-terminal Lys-Lys-X-X sequence.

Proteins modified with a mannose-6-phosphate localize exclusively to the lysosome.

3 B) Which of the following statements regarding clathrin-coated vesicles is FALSE?

Adapter complexes provide the specificity of vesicle cargo.

Membrane proteins containing a Tyr-X-X-? sequence are recruited into clathrin/AP3 coats.

Clathrin-coated vesicle assembly is mediated by the GTPase ARF.

Dynamin is required for pinching off clathrin-coated vesicles.

Explanation / Answer

3 A) The di-arginine sorting sequence can be located anywhere in the cytoplasmic domain of an ER-resident protein.

Reason: It should be located at specific location e.g. at N-terminus of cytoplasmic domain.

3B) Membrane proteins containing a Tyr-X-X-? sequence are recruited into clathrin/AP3 coats.

Reason: They interact with AP2 assembly particles not with AP3.