2qqh

From Proteopedia

Structure of C8a-MACPF reveals mechanism of membrane attack in complement immune defense

Overview

Membrane attack is important for mammalian immune defense against invading, microorganisms and infected host cells. Proteins of the complement, membrane attack complex (MAC) and the protein perforin share a common, MACPF domain that is responsible for membrane insertion and pore, formation. We determined the crystal structure of the MACPF domain of, complement component C8alpha at 2.5 angstrom resolution and show that it, is structurally homologous to the bacterial, pore-forming, cholesterol-dependent cytolysins. The structure displays two regions that, (in the bacterial cytolysins) refold into transmembrane beta hairpins, forming the lining of a barrel pore. Local hydrophobicity explains why, C8alpha is the first complement protein to insert into the membrane. The, size of the MACPF domain is consistent with known C9 pore sizes. These, data imply that these mammalian and bacterial cytolytic proteins share a, common mechanism of membrane insertion.

Disease

Known disease associated with this structure: C8 deficiency, type I OMIM:[120950]

About this Structure

2QQH is a Single protein structure of sequence from Homo sapiens with SO4 and NI as ligands. Full crystallographic information is available from OCA.

Reference

Structure of C8alpha-MACPF reveals mechanism of membrane attack in complement immune defense., Hadders MA, Beringer DX, Gros P, Science. 2007 Sep 14;317(5844):1552-4. PMID:17872444

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