Calponin 1

Calponin 1 is a basic smooth muscle protein that in humans is encoded by the CNN1 gene.

The CNN1 gene is located at 19p13.2-p13.1 in the human chromosomal genome and contains 7 exons, encoding the protein calponin 1, an actin filament-associated regulatory protein. Human calponin 1 is a 33.2-KDa protein consists of 297 amino acids with an isoelectric point of 9.1, thus calponin 1 is also known as basic calponin.

Evolution

Three homologous genes, Cnn1, Cnn2 and Cnn3, have evolved in vertebrates, encoding three isoforms of calponin: calponin 1, calponin 2, calponin 3, respectively. Protein sequence alignment shows that calponin 1 is highly conserved in mammals but more diverged among lower vertebrates.

Smooth muscle-specific expression

The expression of CNN1 is specific to differentiated mature smooth muscle cells, suggesting a role in contractile functions. Calponin 1 is up-regulated in smooth muscle tissues during postnatal development with a higher content in phasic smooth muscle of the digestive tract.