What does the ER signal recognition particle bind to? Select one: a. The signal recognition particle receptor. b. The signal sequence and the mRNA to be translated. c. Ran-GTP. d. The signal recognition particle receptor and part of the protein to be translocated.

What does the ER signal recognition particle bind to?
Select one:
a. The signal recognition particle receptor.
b. The signal sequence and the mRNA to be translated.
c. Ran-GTP.
d. The signal recognition particle receptor and part of the protein to be translocated.

Answer

• d. The signal recognition particle receptor and part of the protein to be translocated.
  Explanation:
  Endoplasmic Reticulum microsomal membranes contain signal recognition particles which binds to the signal sequence temporarily blocking translation, and eventually binding the ribosome to the ER membranes.

• SRP binds to signal sequence on the newly synthesized protein as it emerges from the ribosome.
• The complex formed is targedted to the translocon in the endoplasmic reticulum membrane.
• The interaction between the complex and the endoplasmic reticulum is by binding to the SRP receptor near the translocon

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