What is usually the retrieval signal for ER integral membrane proteins,like the SRP receptor?
A)KKXX at the C-terminus of the protein
B)KDEL at the C-terminus of the protein
C)KDEL at the N-terminus of the protein
D)KKXX at the N-terminus of the protein
E)KXEL at the C-terminus of the protein

Question

Quizplus · Accepted Answer

KKXX is a signal sequence recognized by the retrieval machinery for ER integral membrane proteins. It is usually located at the C-terminus of the protein and assists in returning the protein back to the ER if it has escaped to other organelles. The SRP receptor is an ER integral membrane protein that recognizes the signal sequence KKXX for retrieval. The other options (B, C, D, E) are also signal sequences, but they are recognized by different machinery and serve different purposes in protein targeting and trafficking.

What Is Usually the Retrieval Signal for ER Integral Membrane