Smoothelin (SMTN)

Smoothelin is a structural protein that is found exclusively in contractile smooth muscle cells. It associates with stress fibers and constitutes part of the cytoskeleton. This gene is localized to chromosome 22q12.3, distal to the TUPLE1 locus and outside the DiGeorge syndrome deletion. Alternative splicing of this gene results in three transcript variants.This gene, termed smoothelin (SMTN), encodes a 371-amino acid polypeptide. Sequence analysis revealed that the protein contains a 56-amino acid domain with significant homology to a sequence that flanks the actin-binding domains of dystrophin, utrophin, beta-spectrin, and alpha-actinin. Cell fractionation studies suggested to the authors that smoothelin is a part of the cytoskeleton.