A TIGHTLY BOUND CHROMOSOME ANTIGEN IS DETECTED BY MONOCLONAL-ANTIBODIES IN A RING-LIKE STRUCTURE ON HUMAN CENTROMERES

Monoclonal antibodies (Mabs) were raised against isolated Chinese hams ter protein-depleted chromosomes Chromosome scaffolds) in order to pro be for components involved in the higher-order structure of mammalian chromosomes. One of the Mabs detected a ring-like structure in metapha se at the centromere, which is conserved between Chinese hamster and h uman cells. Additionally, the Mab stained the centrioles in interphase cells in these two species. The antigen was enriched in chromosomal p rotein preparations by comparison with nuclear protein samples, and ha s an apparent Mr=170,000. The centromere antigen remained present in c hromosome scaffold preparations, indicating that it was tightly associ ated with DNA. The antigen was distinct in its centromeric localisatio n from any of the centromere antigens reported to date. A possible rol e of the antigen in stabilising the centromere, by holding the sister chromatids together until their separation at the metaphase-anaphase t ransition is presented.