Caldesmon (CaD)

Caldesmon is an actin and tropomyosin binding proten. It can be a substrate for ERK1/2. We have hypothesized that the C-terminal end of CaD binds actin and blocks actin-myosin interactions until the phosphorylation of CaD by ERK.This phosphorylation is proposed to cause a conformational change (exaggerated in diagram) which allows increased actin-myosin interactions. The N-terminal end of CaD is thought to tether CaD (and the attached actin) to myosin. Disruption of this tethering with an N-terminal CaD peptide disrupts the placement of the C-terminal end of CaD relative to the myosin head and improves actin-myosin interactions. [Lee et al 1999]