PROSITE documentation PDOC00808
Calponin-like repeat signature and profile


Calponin [1,2] is a thin filament-associated protein that is implicated in the regulation and modulation of smooth muscle contraction. It is capable of binding to actin, calmodulin, troponin C and tropomyosin. The interaction of calponin with actin inhibits the actomyosin MgATPase activity. Calponin is a basic protein of approximately 34 Kd. Multiple isoforms are found in smooth muscles.

Calponin contains three repeats of a well conserved motif of about 26 amino acids. Such a domain is also found in a number of other proteins whose physiological role is not yet established:

  • Vertebrate transgelin (also known as smooth muscle protein SM22-α) (1 copy).
  • Mammalian transgelin 2.
  • Drosophila synchronous flight muscle protein SM20 (1 copy).
  • Rat neuronal protein NP25 [3] (1 copy).
  • Caenorhabditis elegans protein unc-87 [4] (5 copies).
  • An Onchocerca volvulus antigen [5] (5 copies).

Most of these proteins also contain a N-terminal CH domain (see <PDOC50021>). The calponin-like repeat is a short actin-binding module. Actin-binding sites formed by either CH domains or calponin-like repeats occupy non-competing binding sites along the actin filament [6].

We developed both a pattern and a profile for the calponin-like repeat. The signature pattern corresponds to the first 20 residues, whereas the profile covers the entire calponin-like repeat.

Last update:

June 2005 / Profile added and text revised.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

CALPONIN_2, PS51122; Calponin-like repeat profile  (MATRIX)

CALPONIN_1, PS01052; Calponin-like repeat signature  (PATTERN)


1AuthorsWinder S.J. Walsh M.P.
TitleCalponin: thin filament-linked regulation of smooth muscle contraction.
SourceCell. Signal. 5:677-686(1993).
PubMed ID8130072

2AuthorsApplegate D.E. Feng W. Green R.S. Taubman M.B.
TitleCloning and expression of a novel acidic calponin isoform from rat aortic vascular smooth muscle.
SourceJ. Biol. Chem. 269:10683-10690(1994).
PubMed ID8144658

3AuthorsRen W.-Z. Ng G.Y.K. Wang R.-X. Wu P.H. O'Dowd B.F. Osmond D.H. George S.R. Liew C.-C.
TitleThe identification of NP25: a novel protein that is differentially expressed by neuronal subpopulations.
SourceBrain Res. Mol. Brain Res. 22:173-185(1994).
PubMed ID8015377

4AuthorsGoetinck S.D. Waterston R.H.
TitleThe Caenorhabditis elegans muscle-affecting gene unc-87 encodes a novel thin filament-associated protein.
SourceJ. Cell Biol. 127:79-93(1994).
PubMed ID7929573

5AuthorsIrvine M. Huima T. Prince A.M. Lustigman S.
TitleIdentification and characterization of an Onchocerca volvulus cDNA clone encoding a highly immunogenic calponin-like protein.
SourceMol. Biochem. Parasitol. 65:135-146(1994).
PubMed ID7935620

6AuthorsLener T. Burgstaller G. Gimona M.
TitleThe role of calponin in the gene profile of metastatic cells: inhibition of metastatic cell motility by multiple calponin repeats.
SourceFEBS Lett. 556:221-226(2004).
PubMed ID14706854

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