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PROSITE documentation PDOC51808 |
Twin CX(9)C proteins constitute a large protein family among all eukaryotes. They adopt a coiled coil-helix-coiled coil helix (CHCH) fold stabilized by two disulfide bonds which are formed by the four cysteines in the twin CX(9)C motifs (i.e. two pairs of cysteines each spaced by nine residues). The large majority of twin CX(9)C proteins contains a single CHCH domain, while the others contain two. In those containing a single CHCH domain, this is most frequently located in the central part of the sequence, with C-terminal and N-terminal CHCH domains being less common. In those containing two CHCH domains, these are separated by a few amino acids and, taken together, typically cover a large central part of the sequence. A strong link exists between twin CX(9)C proteins and mitochondrial metabolism. Twin CX(9)C proteins are involved in a limited number of tasks, most if not all of which are performed in the mitochondrial inter-membrane space (IMS), and which include being part of protein complexes, participating in cytochrome c oxidase (COX) assembly, and maintaining mitochondrial structure. The functions of most twin CX(9)C proteins vary around the common theme of playing a scaffolding role which can tie their observed roles in mitochondrial structure and function [1,2,3].
The CHCH domain contains two α-helices (α1 and α2), which form an antiparallel α-hairpin that is covalently paired by two disulfide bridges (see <PDB:4YTV>) [4,5].
Some proteins known to contain a CHCH domain are listed below:
The profile we developed covers the entire CHCH domain.
Last update:August 2016 / First entry.
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PROSITE method (with tools and information) covered by this documentation:
1 | Authors | Westerman B.A. Poutsma A. Steegers E.A.P. Oudejans C.B.M. |
Title | C2360, a nuclear protein expressed in human proliferative cytotrophoblasts, is a representative member of a novel protein family with a conserved coiled coil-helix-coiled coil-helix domain. | |
Source | Genomics 83:1094-1104(2004). | |
PubMed ID | 15177562 | |
DOI | 10.1016/j.ygeno.2003.12.006 |
2 | Authors | Cavallaro G. |
Title | Genome-wide analysis of eukaryotic twin CX9C proteins. | |
Source | Mol. Biosyst. 6:2459-2470(2010). | |
PubMed ID | 20922212 | |
DOI | 10.1039/c0mb00058b |
3 | Authors | Longen S. Bien M. Bihlmaier K. Kloeppel C. Kauff F. Hammermeister M. Westermann B. Herrmann J.M. Riemer J. |
Title | Systematic analysis of the twin cx(9)c protein family. | |
Source | J. Mol. Biol. 393:356-368(2009). | |
PubMed ID | 19703468 | |
DOI | 10.1016/j.jmb.2009.08.041 |
4 | Authors | Banci L. Bertini I. Ciofi-Baffoni S. Jaiswal D. Neri S. Peruzzini R. Winkelmann J. |
Title | Structural characterization of CHCHD5 and CHCHD7: two atypical human twin CX9C proteins. | |
Source | J. Struct. Biol. 180:190-200(2012). | |
PubMed ID | 22842048 | |
DOI | 10.1016/j.jsb.2012.07.007 |
5 | Authors | Watanabe Y. Tamura Y. Kawano S. Endo T. |
Title | Structural and mechanistic insights into phospholipid transfer by Ups1-Mdm35 in mitochondria. | |
Source | Nat. Commun. 6:7922-7922(2015). | |
PubMed ID | 26235513 | |
DOI | 10.1038/ncomms8922 |