IDENTIFICATION OF A NEW MAMMALIAN CENTRIN GENE, MORE CLOSELY-RELATED TO SACCHAROMYCES-CEREVISIAE CDC31 GENE

Among the numerous centrin isoforms identified by two-dimensional gel electrophoresis in human cells, an acidic and slow-migrating isoform i s particularly enriched in a centrosome fraction, We report here that this isoform specifically reacts with antibodies raised against Saccha romyces cerevisiae Cdc31p and is present, as other centrin isoforms, i n the distal lumen of centrioles, It is encoded by a new centrin gene, which we propose to name HsCEN3 (Homo sapiens centrin gene 3), This g ene is more closely related to the yeast CDC31 gene, and shares less i dentity with algae centrin than HsCEN1 and HsCEN2, A murine CDC31-rela ted gene was also found that shows 98% identity and 100% similarity wi th HsCEN3, demonstrating a higher interspecies conservation than the m urine centrin gene MmCEN1 (Mus musculus centrin gene 1) with either Hs CEN1, or HsCEN2, Finally, immunological data suggest that a CDC31-rela ted gene could exist in amphibians and echinoderms as well, All togeth er, our data suggest the existence of two divergent protein subfamilie s in the current centrin family, which might be involved in distinct c entrosome-associated functions. The possible implication of this new m ammalian centrin gene in centrosome duplication is discussed.