Blog
About

  • Record: found
  • Abstract: found
  • Article: not found

A chloroplast homologue of the signal recognition particle subunit SRP54 is involved in the posttranslational integration of a protein into thylakoid membranes.

Proceedings of the National Academy of Sciences of the United States of America

isolation & purification, metabolism, Intracellular Membranes, Kinetics, Light-Harvesting Protein Complexes, Mammals, Organelles, Photosynthetic Reaction Center Complex Proteins, biosynthesis, Protein Binding, Protein Processing, Post-Translational, Recombinant Proteins, Signal Recognition Particle, Animals, Chloroplasts

Read this article at

ScienceOpenPMC
Bookmark
      There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

      Abstract

      The mechanisms involved in the integration of proteins into the thylakoid membrane are largely unknown. However, many of the steps of this process for the light-harvesting chlorophyll a/b protein (LHCP) have been described and reconstituted in vitro. LHCP is synthesized as a precursor in the cytosol and posttranslationally imported into chloroplasts. Upon translocation across the envelope membranes, the N-terminal transit peptide is cleaved, and the apoprotein is assembled into a soluble "transit complex" and then integrated into the thylakoid membrane via three transmembrane helices. Here we show that 54CP, a chloroplast homologue of the 54-kDa subunit of the mammalian signal recognition particle (SRP54), is essential for transit complex formation, is present in the complex, and is required for LHCP integration into the thylakoid membrane. Our data indicate that 54CP functions posttranslationally as a molecular chaperone and potentially pilots LHCP to the thylakoids. These results demonstrate that one of several pathways for protein routing to the thylakoids is homologous to the SRP pathway and point to a common evolutionary origin for the protein transport systems of the endoplasmic reticulum and the thylakoid membrane.

      Related collections

      Author and article information

      Journal
      42047
      7731984

      Comments

      Comment on this article