2002/05/18 by Elliott M. Kanner, Irene Klein, Martin Friedlander +1 · 2 citations
Biochemistry, Genetics and Molecular Biology · #Lipid Membrane Structure and Behavior #RNA and protein synthesis mechanisms #Receptor Mechanisms and Signaling
paper · doi:10.1021/bi0256882
openalex publication_date 2002/05/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22
Opsin, a member of the G-protein-coupled receptor family, is a polytopic membrane protein that does not encode a cleaved amino-terminal signal sequence. The amino terminus of opsin precedes the first known targeting information, suggesting that it translocates across the endoplasmic reticulum (ER) membrane after synthesis, uncoupled from translation. However, translocation across the mammalian ER is believed to be coupled to protein synthesis. In this study we show that opsin, within a range of nascent peptide lengths, targets and translocates equally efficiently co- and posttranslationally. Longer nascent opsin peptides have a lower efficiency of cotranslational translocation but an even lower efficiency of posttranslational translocation. We also show that SRP is required for both co- and posttranslational targeting.