The following are steps that occur when a protein is targeted for synthesis on the endoplasmic reticulum (ER). Which of the following indicates the correct sequence for the signal mechanism that targets proteins for the ER?
The SRP leaves and polypeptide synthesis resumes, with simultaneous translocation across the membrane.
Polypeptide synthesis begins on a free ribosome in the cytosol.
An SRP binds to the signal peptide, halting synthesis momentarily.
The rest of the completed polypeptide leaves the ribosome and folds into its final conformation.
The SRP binds to a receptor protein in the ER membrane that is part of a protein complex that forms a pore.
The signal peptide is cleaved by an enzyme in the receptor protein complex.
a) 2,3,5,1,6,4
b) 2,3,5,6,1,4
c) 3,1,6,5,2,4
d) 3,2,1,5,6,4
The correct sequence for the signal mechanism that targets proteins for the ER is:
b) 2,3,5,6,1,4