Targeting of an abundant cytosolic form of the protein import receptor at Toc159 to the outer chloroplast membrane

Citation
A. Hiltbrunner et al., Targeting of an abundant cytosolic form of the protein import receptor at Toc159 to the outer chloroplast membrane, J CELL BIOL, 154(2), 2001, pp. 309-316
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell & Developmental Biology
Journal title
JOURNAL OF CELL BIOLOGY
ISSN journal
0021-9525 → ACNP
Volume
154
Issue
2
Year of publication
2001
Pages
309 - 316
Database
ISI
SICI code
0021-9525(20010723)154:2<309:TOAACF>2.0.ZU;2-N
Abstract
Chloroplast biogenesis requires the large-scale import of cytosolically syn thesized precursor proteins. A trimeric translocon (Toc complex) containing two homologous, GTP-binding proteins (atToc33 and atToc159) and a channel protein (atToc75) facilitates protein translocation across the outer envelo pe membrane. The mechanisms governing function and assembly of the Toc comp lex are not yet understood. This study demonstrates that atToc159 and its p ea orthologue exist in an abundant, previously unrecognized soluble form, a nd partition between cytosol-containing soluble fractions and the chloropla st outer membrane. We show that soluble atToc159 binds directly to the cyto solic domain of atToc33 in a homotypic interaction, contributing to the int egration of atToc159 into the chloroplast outer membrane. The data suggest that the function of the Toc complex involves switching of at Toc159 betwee n a soluble and an integral membrane form.