1na8

From Proteopedia

Revision as of 10:54, 20 March 2008

Crystal structure of ADP-ribosylation factor binding protein GGA1

Overview

The adaptor appendage domains are believed to act as binding platforms for coated vesicle accessory proteins. Using glutathione S-transferase pulldowns from pig brain cytosol, we find three proteins that can bind to the appendage domains of both the AP-1 gamma subunit and the GGAs: gamma-synergin and two novel proteins, p56 and p200. p56 elicited better antibodies than p200 and was generally more tractable. Although p56 and gamma-synergin bind to both GGA and gamma appendages in vitro, immunofluorescence labeling of nocodazole-treated cells shows that p56 colocalizes with GGAs on TGN46-positive membranes, whereas gamma-synergin colocalizes with AP-1 primarily on a different membrane compartment. Furthermore, in AP-1-deficient cells, p56 remains membrane-associated whereas gamma-synergin becomes cytosolic. Thus, p56 and gamma-synergin show very strong preferences for GGAs and AP-1, respectively, in vivo. However, the GGA and gamma appendages share the same fold as determined by x-ray crystallography, and mutagenesis reveals that the same amino acids contribute to their binding sites. By overexpressing wild-type GGA and gamma appendage domains in cells, we can drive p56 and gamma-synergin, respectively, into the cytosol, suggesting a possible mechanism for selectively disrupting the two pathways.

About this Structure

1NA8 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

Reference

Binding partners for the COOH-terminal appendage domains of the GGAs and gamma-adaptin., Lui WW, Collins BM, Hirst J, Motley A, Millar C, Schu P, Owen DJ, Robinson MS, Mol Biol Cell. 2003 Jun;14(6):2385-98. Epub 2003 Mar 20. PMID:12808037

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