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Title: Dimerization of TOC receptor GTPases and its implementation for the control of protein import into chloroplasts
Authors: Aronsson, Henrik
Jarvis, Paul
First Published: 13-May-2011
Publisher: Portland Press
Citation: Biochemical Journal, 2011, 436 (2), pp. e1-e2
Abstract: Pre-protein import into chloroplasts is facilitated by multiprotein translocon complexes in the envelope membranes. Major components of the TOC (translocon at the outer envelope membrane of chloroplasts) complex are the receptor proteins Toc33 and Toc159. These two receptors are related GTPases, and they are predicted to engage in homodimerization and/or heterodimerization. Although such dimerization has been studied extensively, its exact function in vivo remains elusive. In this issue of the Biochemical Journal, Oreb et al. present evidence that homodimerization of Toc33 prevents nucleotide exchange, thereby locking the receptor in the GDP-loaded state and preventing further activity. Pre-protein arrival is proposed to release this lock, through disruption of the dimer and subsequent nucleotide exchange. The Toc33-bound pre-protein is then able to progress to downstream steps in the translocation mechanism, with GTP hydrolysis defining another important control point as well as preparing the receptor for the next pre-protein client. These new results are discussed in the context of previous findings pertaining to TOC receptor dimerization and function.
DOI Link: 10.1042/BJ20110659
ISSN: 0264-6021
eISSN: 1470-8728
Type: Journal Article
Rights: © The Authors, Journal compilation © 2011 Biochemical Society.
Description: Metadata only entry
Appears in Collections:Published Articles, Dept. of Biology

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