The domain within your query sequence starts at position 206 and ends at position 304; the E-value for the CH domain shown below is 3.52e-20.



Calponin homology domain
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):

A number of actin-binding proteins, including spectrin, alpha-actinin and fimbrin, contain a 250 amino acid stretch called the actin binding domain (ABD). The ABD has probably arisen from duplication of a domain which is also found in a single copy in a number of other proteins like calponin or the vav proto-oncogene and has been called calponin homology (CH) domain [ (PUBMED:9708889) (PUBMED:9887274) ].

A detailed analysis of The CH domain-containing proteins has shown that they can be divided in three groups [ (PUBMED:9708889) ]:

  • The fimbrin family of monomeric actin cross-linking molecules containing two ABDs
  • Dimeric cross-linking proteins (alpha-actinin, beta-spectrin, filamin, etc.) and monomeric F-actin binding proteins (dystrophin, utrophin) each containing one ABD
  • Proteins containing only a single amino terminal CH domain.

Each single ABD, comprising two CH domains, is able to bind one actin monomer in the filament. The N-terminal CH domain has the intrinsic ability to bind actin, albeit with lower affinity than the complete ABD, whereas the C-terminal CH bind actin extremely weakly or not at all. Nevertheless both CH domains are required for a fully functional ABD; the C-terminal CH domain contributing to the overall stability of the complete ABD through inter-domain helix-helix interactions [ (PUBMED:9708889) ]. Some of the proteins containing a single CH domain also bind to actin, although this has not been shown to be via the single CH domain alone [ (PUBMED:9887274) ]. In addition, the CH domain occurs also in a number of proteins not known to bind actin, a notable example being the vav protooncogene.

The resolution of the 3D structure of various CH domains has shown that the conserved core consist of four major alpha-helices [ (PUBMED:9887274) ].

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 66728 CH domains in 45684 proteins in SMART's nrdb database.

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