Calponin

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
Entrez 1264
HUGO 2155
OMIM 600806
PDB 1WYP
RefSeq NM_001299
UniProt P51911
Other data
Locus Chr. 19 p13.2-13.1
calponin 2
Identifiers
Symbol CNN2
Entrez 1265
HUGO 2156
OMIM 602373
RefSeq NM_004368
UniProt Q99439
Other data
Locus Chr. 21 q11.1
calponin 3, acidic
Identifiers
Symbol CNN3
Entrez 1266
HUGO 2157
OMIM 602374
RefSeq NM_001839
UniProt Q6FHA7
Other data
Locus Chr. 1 p22-p21

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.

Sturcture 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. Calponin does not bind to actin in the CH domain as generally described due to the fact that the CH domain is known to bind calcium to calmodulin which then inhibits actin binding. Calponin is responsible for binding many actin binding proteins, phospholipids, and regulates the actin/myosin interaction. Calponin is also thought to negatively effect the bone making process due to being expressed in high amounts in osteoblasts.[2]

References

  1. ^ PDB 1WYP; Tomizawa T, Kigawa T, Koshiba S, Inoue M, Yokoyama S. "RCSB PDB - 1WYP Structure Summary". RCSB Protein Data Bank. doi:10.2210/pdb1wyp/pdb. http://www.pdb.org/pdb/explore/explore.do?structureId=1WYP. 
  2. ^ Maciver S. "The Calponin Family". Department of Biomedical Sciences, University of Edinburgh. http://www.bms.ed.ac.uk/research/others/smaciver/Cyto-Topics/Calponin_Family.htm. Retrieved 2011-04-25. 

External links