The signal-recognition particle (SRP) ...
A) is a heterodimeric protein.
B) transiently inhibits translation and polypeptide elongation by binding to and inhibiting the elongation factors.
C) accompanies the nascent polypeptide all the way into the ER lumen.
D) binds GTP.
E) is permanently attached to the cytosolic face of the ER membrane, thus bringing the ribosomes into close proximity of the translocon.

Question

Quizplus · Accepted Answer

SRP is a ribonucleoprotein particle that recognizes endoplasmic reticulum (ER) signal sequences in nascent polypeptides, stalls the ribosome by inhibiting elongation factor binding, and docks the ribosome onto the translocon channel for protein import into the ER. Both SRP and its receptor on the ER membrane can bind and hydrolyze GTP.

The Signal-Recognition Particle (SRP)