Mammalian kinetochore/centromere composition: a 50 kDa antigen is present in the mammalian kinetochore/centromere.

The composition of the mammalian kinetochore/centromere was studied by indirect immunofluorescence and immunoblotting protocols using serum from a patient with the CREST variant of scleroderma. The results of these studies suggest that a protein with a molecular weight of 50 kDa is localized at the surface of the primary constrictions (the kinetochore region) of both human and Indian muntjac chromosomes. In addition, we were able to verify the presence of a 19.5 kDa antigen (CENP-A), previously detected in human centromeres, within the kinetochore region of the Indian muntjac. These data suggest that the composition of the kinetochore region of the primary constriction is complex and that there is conservation in composition within the mammals. These features may reflect the important role of this unique chromosomal domain in the maintenance of ploidy.