Characterization of a polypeptide associated with coated vesicles and the cytoskeleton which is recognized by a CREST serum.

Serum from an individual with the CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dismotility, sclerodactyly, telangiectasia) reacts not only with kinetochores, but also with a cytoplasmic, phosphorylatable polypeptide, which is shown by immunofluorescence in whole cells and immunoelectronmicroscopy in sections to be associated with actin stress fibres in cultured mammalian cells. The antigen shows some variation in molecular weight between species, estimated by immunoblotting to range from 68 to 76 kD between mouse, Chinese hamster, sheep and human cells. Much of the polypeptide copurifies with coated vesicles, of which approx. 5% bound antibody from the serum, as detected by immunogold electronmicroscopy.