Proteins with a C-terminal transmembrane sequence are
A) cotranslationally brought to the ER by SRP, where they are inserted into the ER lumen.
B) posttranslationally brought to the ER by TRC40, where they remain in the ER membrane with their N-terminal domain facing the lumen.
C) posttranslationally brought to the ER by SRP, where they remain in the ER membrane with their N-terminal domain facing the lumen.
D) posttranslationally brought to the ER by TRC40, where they remain in the ER membrane with their C-terminal domain facing the lumen.

Question

Quizplus · Accepted Answer

Proteins with a C-terminal transmembrane sequence are typically posttranslationally targeted to the ER membrane via the TRC40 pathway. Once inserted into the ER membrane, their N-terminal domain faces the lumen, which is consistent with the topology described in option B.

Proteins with a C-Terminal Transmembrane Sequence Are