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]

Immunohistochemistry for calponin in ductal carcinoma in situ, highlighting myoepithelial cells around all tumor cells, thereby ruling out invasive ductal carcinoma.

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. {{cite journal}}: Cite journal requires |journal= (help)
  2. ^ Ferjani, I; Fattoum, A; Manai, M; Benyamin, Y; Roustan, C; Maciver, SK (September 2010). "Two distinct regions of calponin share common binding sites on actin resulting in different modes of calponin-actin interaction". Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics. 1804 (9): 1760–7. doi:10.1016/j.bbapap.2010.05.012. PMID 20595006.
  3. ^ Maciver S. "The Calponin Family". Department of Biomedical Sciences, University of Edinburgh. Retrieved 2011-04-25.


Allikas: https://en.wikipedia.org/wiki/Calponin
No tags for this post.