Calponin Homology Domain
CH domain from H.Sapiends Calponin 1. PDB 1wyp
Identifiers
Symbol	CH
Pfam	PF00307
Pfam clan	CL0188
InterPro	IPR001715
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

calponin 1, basic, smooth muscle
Solution structure of the CH domain of human Calponin 1. Rainbow colored cartoon ( N-terminus = blue, C-terminus = red). [1]
Identifiers
Symbol	CNN1
NCBI gene	1264
HGNC	2155
OMIM	600806
PDB	1WYP
RefSeq	NM_001299
UniProt	P51911
Other data
Locus	Chr. 19 p13.2-13.1
Search for Structures Swiss-model Domains InterPro

Calponin is a calcium binding protein. Calponin tonically inhibits the ATPase activity of myosin in smooth muscle. Phosphorylation of calponin by a protein kinase, which is dependent upon calcium binding to calmodulin, releases the calponin's inhibition of the smooth muscle ATPase.

Structure and function

Calponin is mainly made up of α-helices with hydrogen bond turns. It is a binding protein and is made up of three domains. These domains in order of appearance are Calponin Homology (CH), regulatory domain (RD), and Click-23, domain that contains the calponin repeats. At the CH domain calponin binds to α-actin and filamin and binds to actin within the RD domain. Calmodulin, when activated by calcium may bind weakly to the CH domain and inhibit calponin binding with α-actin. ^[2] Calponin is responsible for binding many actin binding proteins, phospholipids, and regulates the actin/myosin interaction. Calponin is also thought to negatively affect the bone making process due to being expressed in high amounts in osteoblasts. ^[3]

References

External links

• Calponin at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

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