does kinetochore autoantigen CENP-C constitute a kinetochore organizing center?
Kinetochore is morphologically defined as a trilaminated, highly differentiated structure at the primary constriction of mitotic chromosomes. This subcellular organella is assumed to be composed of DNA and proteins. Immunoelectron microscopy has shown that centromere autoantigens CENP-C and CENP-B localize to the kinetochore inner plate and the underlying centromeric region respectively. We previously indicated that both are DNA-binding proteins that constitute centromeric heterochromatin throughout the cell cycle. Here, we tried to elucidate how these molecules are involved in the kinetochore/centromere organization in vivo by analyzing their morphological behavior in nuclei. Using immunofluorescence microscopy, we found that CENP-C remained as round discrete dots, whereas CENP-B displayed larger surrounding materials. To examine the CENP-C-binding locus on the genome, we prepared highly extended chromatin fibers and performed simultaneous immunofluorescence and fluorescence in situ h
