Calponin homology domain (IPR001715)

Short name: CH-domain

Overlapping homologous superfamilies

Domain relationships


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 [PMID: 9708889, PMID: 9887274].

A detailed analysis of The CH domain-containing proteins has shown that they can be divided in three groups [PMID: 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 amino terminal CH domain has the intrinsic ability to bind actin, albeit with lower affinity than the complete ABD, whereas the carboxy 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 [PMID: 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 [PMID: 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 [PMID: 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 [PMID: 11839310].
  • Beta-spectrin, a major component of a submembrane cytoskeletal network connecting actin filaments to integral plasma membrane proteins [PMID: 17121810].
  • The actin-cross-linking domain of the fimbrin/plastin family of actin filament bundling or cross-linking proteins [PMID: 9302997].
  • Utrophin,a close homologue of dystrophin [PMID: 9887274].
  • Dystrophin, the protein found to be defective in Duchenne muscular dystrophy; this protein contains a tandem repeat of two CH domains [PMID: 10801490].
  • Actin-binding domain of plectin, a large and widely expressed cytolinker protein [PMID: 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 [PMID: 12857735].
  • Ras GTPase-activating-like protein rng2, an IQGAP protein that is essential for the assembly of an actomyosin ring during cytokinesis [PMID: 15272162].
  • Transgelin, which suppresses androgen receptor transactivation [PMID: 17082327].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0005515 protein binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE profiles