Fesselin: a novel synaptopodin-like actin binding protein from muscle tissue

A novel actin binding protein has been isolated from chicken gizzard muscle. When isolated, a pair of proteins with apparent molecular weights of 79 kDa and 103 kDa are obtained; both proteins have a pI near 9.3. Peptide mapping indicates that these proteins are related. Antibodies against this protein cross-reacted with proteins from other smooth muscle containing tissues as well as skeletal and heart muscle. Traces of cross-reactive material were also detected in brain and kidney tissue. The affinity of this protein for actin is ca. 1x10(6) M(-1). Interestingly, this actin binding protein is a potent actin-bundling agent. A partial sequence analysis confirmed that there were no previously reported homologues in smooth muscle. However, considerable homology was found with the protein synaptopodin that is found in nervous tissue and kidney but is absent from muscle tissue. It is likely that the new protein is a member of the synaptopodin family. We call the smooth muscle actin binding protein fesselin.