Guanosine triphosphate promotes the post-translational integration of opsin into the endoplasmic reticulum membrane

UMMS Affiliation

Department of Biochemistry

Publication Date


Document Type



Animals; Dogs; Electrophoresis, Polyacrylamide Gel; Endoplasmic Reticulum; Eye Proteins; GTP-Binding Proteins; Glycosylation; Guanosine Triphosphate; Opsin; Pancreas; *Protein Processing, Post-Translational; RNA, Messenger


Biochemistry | Life Sciences | Medicine and Health Sciences


Membrane integration of a nascent opsin polypeptide was examined to determine whether insertion of proteins into the endoplasmic reticulum is dependent upon energy provided by ribonucleotide triphosphate hydrolysis. A discrete-sized nascent chain was obtained by in vitro translation of a mRNA which lacked a termination codon yet encoded the first 156 residues of bovine opsin. Ribosomes bearing the newly synthesized opsin chains were post-translationally incubated with canine pancreas microsomal membrane vesicles after addition of exogenous ribonucleotides or ribonucleotide analogues. Post-translational membrane integration and glycosylation of the 156-residue nascent polypeptide was found to require either the presence of guanosine triphosphate or a nonhydrolyzable GTP analogue. ATP did not promote post-translational integration of the nascent polypeptide. Although ribonucleotide hydrolysis was not obligatorily required for integration of opsin, we observed an increase in the proportion of glycosylated opsin chains in post-translational incubations that contained hydrolyzable ribonucleotide triphosphates. We conclude that a GTP-binding protein performs an essential role during integration of opsin into the endoplasmic reticulum.


J Biol Chem. 1988 Mar 25;263(9):4381-5.

Journal/Book/Conference Title

The Journal of biological chemistry

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