Transgelin (TAGLN)

Transgelin is a transformation and shape-change sensitive actin cross-linking/gelling protein found in fibroblasts and smooth muscle. Its expression is down-regulated in many cell lines, and this down-regulation may be an early and sensitive marker for the onset of transformation. A functional role of this protein is unclear. In contrast to fast and slow skeletal muscle cells that fuse and terminally differentiate, smooth muscle cells are able to simultaneously proliferate and express lineage-restricted proteins. One of these proteins, expressed exclusively in smooth muscles, has been referred to as SM22-alpha, a 22-kD protein with structural similarity to the vertebrate thin filament myofibrillar regulatory protein calponin and the Drosophila muscle protein mp20, neither of which play a direct role in the contractile apparatus.