Cytoskeleton Proteins

Caldesmon is an actin- and myosin-binding protein implicated in the regulation of actomyosin interactions in smooth muscle and nonmuscle cells. Caldesmon stimulates actin binding of tropomyosin which increases the stabilization of actin filament structure. In muscle tissues, caldesmon inhibits the actomyosin ATPase by binding to F-actin. This inhibition is attenuated by calcium-calmodulin and is potentiated by tropomyosin. Caldesmon Iinteracts with actin, myosin, two molecules of tropomyosin and with calmodulin.

Tubulin gamma-1 chain (tubulin-gamma) is the major constituent of microtubules. Tubulin-gamma is found at microtubule organizing centers (MTOC) such as the spindle poles or the centrosome, suggesting that it is involved in the minus-end nucleation of microtubule assembly.

Keratin, type I cytoskeletal 16 (cytokeratin-16) Keratin 16 is expressed in keratinocytes, which are undergoing rapid turnover in the suprabasal region (also known as hyperproliferation-related keratins). Defects in cytokeratin-16 are a cause of pachyonychia congenita type 1 (PC1), also known as Jadassohn-Lewandowsky syndrome. PC1 is an autosomal dominant ectodermal dysplasia characterized by hypertrophic nail dystrophy resulting in onchyogryposis (thickening and increase in curvature of the nail), palmoplantar keratoderma, follicular hyperkeratosis, and oral leukokeratosis.

Gelsolin is a calcium-regulated, actin-modulating protein that binds to the plus (or barbed) ends of actin monomers or filaments, preventing monomer exchange (end-blocking or capping). It can promote the assembly of monomers into filaments (nucleation) as well as sever filaments already formed. Defects in gelsolin are the cause of amyloidosis type 5 (AMYL5), also known as familial amyloidosis Finnish type. AMYL5 is a hereditary generalized amyloidosis due to gelsolin amyloid deposition. It is typically characterized by cranial neuropathy and lattice corneal dystrophy.