Co-translational Targeting and Translocation of the Amino Terminus of Opsin across the Endoplasmic Membrane Requires GTP but Not ATP

2003/02/28 by Elliott M. Kanner, Martin Friedlander, Sanford M. Simon · 1 citation
Biochemistry, Genetics and Molecular Biology · #Endoplasmic Reticulum Stress and Disease #Cellular transport and secretion #Cell death mechanisms and regulation

paper · doi:10.1074/jbc.m207462200

openalex publication_date 2003/02/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23

Abstract

The tight coupling between ongoing translation and translocation across the mammalian endoplasmic reticulum has made it difficult to determine the requirements that are specific for translocation. We have developed an in vitro assay that faithfully mimics the co-translational targeting and translocation of the amino terminus of opsin without ongoing translation. Using this system we demonstrate that this post-translational targeting and translocation requires nucleotide triphosphates but not cytosolic proteins. The addition of GTP alone was sufficient to fully restore targeting. The addition of ATP was not specifically required, and non-hydrolyzable analogs of ATP that blocked 90% of the ATPase activity also had no inhibitory effect on translocation.

Citations

• Translocation of proteins across the endoplasmic reticulum III. Signal recognition protein (SRP) causes signal sequence-dependent and site-specific arrest of chain elongation that is released by microsomal membranes.
• The Amino Terminus of Opsin Translocates “Posttranslationally” as Efficiently as Cotranslationally

Cited by

• Protein targeting [wikipedia]