1h65

From Proteopedia

CRYSTAL STRUCTURE OF PEA TOC34-A NOVEL GTPASE OF THE CHLOROPLAST PROTEIN TRANSLOCON

Overview

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.

About this Structure

1H65 is a Single protein structure of sequence from Pisum sativum with and as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

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

Page seeded by OCA on Thu Feb 21 12:57:50 2008