CH

Calponin homology domain
CH
SMART accession number:SM00033
Description: Actin binding domains present in duplicate at the N-termini of spectrin-like proteins (including dystrophin, alpha-actinin). These domains cross-link actin filaments into bundles and networks. A calponin homology domain is predicted in yeasst Cdc24p.
Interpro abstract (IPR001715):

The calponin homology domain (also known as CH-domain) is a superfamily of actin-binding domains found in both cytoskeletal proteins and signal transduction proteins [(PUBMED:7589522)]. It comprises the following groups of actin-binding domains:

  • Actinin-type (including spectrin, fimbrin, ABP-280) (see IPR001589).
  • Calponin-type (see IPR000557).

A comprehensive review of proteins containing this type of actin-binding domains is given in [(PUBMED:7584474)].

The CH domain is involved in actin binding in some members of the family. However, in calponins there is evidence that the CH domain is not involved in their actin binding activity [(PUBMED:9625744)]. Most proteins have two copies of the CH domain, however some proteins such as calponin and the human vav proto-oncogene (P15498) have only a single copy. The structure of an example CH-domain has recently been solved [(PUBMED:9164454)].

Proteins containing a calponin domain include:

  • Calponin, which is involved in the regulation of contractility and organisation of the actin cytoskeleton in smooth muscle cells [(PUBMED:11839310)].
  • Beta-spectrin, a major component of a submembrane cytoskeletal network connecting actin filaments to integral plasma membrane proteins [(PUBMED:17121810)].
  • The actin-cross-linking domain of the fimbrin/plastin family of actin filament bundling or cross-linking proteins [(PUBMED:9302997)].
  • Utrophin,a close homologue of dystrophin [(PUBMED:9887274)].
  • Dystrophin, the protein found to be defective in Duchenne muscular dystrophy; this protein contains a tandem repeat of two CH domains [(PUBMED:10801490)].
  • Actin-binding domain of plectin, a large and widely expressed cytolinker protein [(PUBMED:15128297)].
  • The N-terminal microtubule-binding domain of microtubule-associated protein eb1 (end-binding protein), a member of a conserved family of proteins that localise to the plus-ends of microtubules [(PUBMED:12857735)].
  • Ras GTPase-activating-like protein rng2, an IQGAP protein that is essential for the assembly of an actomyosin ring during cytokinesis [(PUBMED:15272162)].
  • Transgelin, which suppresses androgen receptor transactivation [(PUBMED:17082327)].

GO function:protein binding (GO:0005515)
Family alignment:
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There are 18580 CH domains in 12554 proteins in SMART's nrdb database.

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