1wy9

File:1wy9.gif

Crystal structure of microglia-specific protein, Iba1

Overview

The ionized calcium-binding adaptor molecule 1 (Iba1) with 147 amino acid residues has been identified as a calcium-binding protein, expressed specifically in microglia/macrophages, and is expected to be a key factor in membrane ruffling, which is a typical feature of activated microglia. We have determined the crystal structure of human Iba1 in a Ca(2+)-free form and mouse Iba1 in a Ca(2+)-bound form, to a resolution of 1.9 A and 2.1 A, respectively. X-ray structures of Iba1 revealed a compact, single-domain protein with two EF-hand motifs, showing similarity in overall topology to partial structures of the classical EF-hand proteins troponin C and calmodulin. In mouse Iba1, the second EF-hand contains a bound Ca(2+), but the first EF-hand does not, which is often the case in S100 proteins, suggesting that Iba1 has S100 protein-like EF-hands. The molecular conformational change induced by Ca(2+)-binding of Iba1 is different from that found in the classical EF-hand proteins and/or S100 proteins, which demonstrates that Iba1 has an unique molecular switching mechanism dependent on Ca(2+)-binding, to interact with target molecules.

About this Structure

1WY9 is a Single protein structure of sequence from Mus musculus. Full crystallographic information is available from OCA.

Reference

X-ray structures of the microglia/macrophage-specific protein Iba1 from human and mouse demonstrate novel molecular conformation change induced by calcium binding., Yamada M, Ohsawa K, Imai Y, Kohsaka S, Kamitori S, J Mol Biol. 2006 Dec 1;364(3):449-57. Epub 2006 Sep 15. PMID:17011575 Page seeded by OCA on Sat May 3 14:17:59 2008

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