Structural highlights
Function
[TOC34_PEA] GTPase involved in protein precursor import into chloroplasts. Seems to recognize chloroplast-destined precursor proteins and regulate their presentation to the translocation channel through GTP hydrolysis.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Toc34, a 34-kDa integral membrane protein, is a member of the Toc (translocon at the outer-envelope membrane of chloroplasts) complex, which associates with precursor proteins during protein transport across the chloroplast outer membrane. Here we report the 2.0 A resolution crystal structure of the cytosolic part of pea Toc34 in complex with GDP and Mg2+. In the crystal, Toc34 molecules exist as dimers with features resembling those found in a small GTPase in complex with a GTPase activating protein (GAP). However, gel filtration experiments revealed that dimeric and monomeric forms of Toc34 coexisted in phosphate saline buffer solution at pH 7.2. Mutation of Arg 128, an essential residue for dimerization, to an Ala residue led to the formation of an exclusively monomeric species whose GTPase activity is significantly reduced compared to that of wild type Toc34. These results, together with a number of structural features unique to Toc34, suggest that each monomer acts as a GAP on the other interacting monomer.
Crystal structure of pea Toc34, a novel GTPase of the chloroplast protein translocon.,Sun YJ, Forouhar F, Li Hm HM, Tu SL, Yeh YH, Kao S, Shr HL, Chou CC, Chen C, Hsiao CD Nat Struct Biol. 2002 Feb;9(2):95-100. PMID:11753431[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Sun YJ, Forouhar F, Li Hm HM, Tu SL, Yeh YH, Kao S, Shr HL, Chou CC, Chen C, Hsiao CD. Crystal structure of pea Toc34, a novel GTPase of the chloroplast protein translocon. Nat Struct Biol. 2002 Feb;9(2):95-100. PMID:11753431 doi:10.1038/nsb744
