Calponin
Calcium binding protein
From Wikipedia, the free encyclopedia
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 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 | ||||||
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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]
