title: The gateway to chloroplast: re-defining the function of chloroplast receptor proteins.
abstract: Chloroplast biogenesis often requires a tight orchestration between gene expression (both plastidial and nuclear) and translocation of ~3000 nuclear-encoded proteins into the organelle. Protein translocation is achieved via two multimeric import machineries at the outer (TOC) and inner (TIC) envelope of chloroplast, respectively. Three components constitute the core element of the TOC complex: a β-barrel protein translocation channel Toc75 and two receptor constituents, Toc159 and Toc34. A diverse set of distinct TOC complexes have recently been characterized and these diversified TOC complexes have evolved to coordinate the translocation of differentially expressed proteins. This review aims to describe the recent discoveries relating to the typical characteristics of these distinct TOC complexes, particularly the receptor constituents, which are the main contributors for TOC complex diversification.
authors.affiliation: Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Grosshadernerstrasse 2-4, D-82152 Planegg-Martinsried, Germany.
authors.forename: Wai-Ling
authors.initials: WL
authors.lastname: Chang
authors.forename: Jürgen
authors.initials: J
authors.lastname: Soll
authors.forename: Bettina
authors.initials: B
authors.lastname: Bölter
mesh_terms: D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D002736:Chloroplasts / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D011498:Protein Precursors; C403444:TOC159 protein, Arabidopsis; C491798:TOC34 protein, Arabidopsis; C491244:TOC75 protein, Arabidopsis; D020558:GTP Phosphohydrolases