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.
Calponin Homology Domain | |||||||||
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Identifiers | |||||||||
Symbol | CH | ||||||||
Pfam | PF00307 | ||||||||
Pfam clan | CL0188 | ||||||||
InterPro | IPR001715 | ||||||||
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calponin 1, basic, smooth muscle | |||||||
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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 | ||||||
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calponin 2 | |||||||
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Identifiers | |||||||
Symbol | CNN2 | ||||||
NCBI gene | 1265 | ||||||
HGNC | 2156 | ||||||
OMIM | 602373 | ||||||
RefSeq | NM_004368 | ||||||
UniProt | Q99439 | ||||||
Other data | |||||||
Locus | Chr. 19 p13.3 | ||||||
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calponin 3, acidic | |||||||
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Identifiers | |||||||
Symbol | CNN3 | ||||||
NCBI gene | 1266 | ||||||
HGNC | 2157 | ||||||
OMIM | 602374 | ||||||
RefSeq | NM_001839 | ||||||
UniProt | Q6FHA7 | ||||||
Other data | |||||||
Locus | Chr. 1 p22-p21 | ||||||
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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]
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