Analysis of the centromeric region of the human Y chromosome

The centromere is an important region of the chromosome which ensures correct segregation at cell division. The DNA sequences which make up human centromeres are poorly understood. An analysis of the human Y chromosome centromere DNA has therefore been undertaken. The structures of 23 yeast artificial chromosomes (YAC) clones and 4 cosmid clones have been determined and these have contributed to a map of ~7Mb of DNA which span the centromere. The centromeric region of the human Y chromosome contains a single major block of tandemly repeating alphoid DNA which is variable in size. The 5.7kb alphoid subunits are all orientated in one direction and become diverged at the edges of the array. Flanking the alphoid DNA are small blocks of other known tandemly repeated sequences, the 5bp, 48bp and 68bp satellites. These satellites are arranged in an asymmetric manner and are interspersed with a range of low to moderate copy number repeats. Only one putative single copy sequence has been detected. Nearby lie two regions of X-Y homology: a more proximal region which contains a gene (amelogenin) and a more distal region which has previously been shown to result from a recent X-Y transposition event. These results show that the centromeric region of the human Y chromosome is a complex mosaic of tandem repeats and other repeats. Furthermore, they provide a detailed map of the region and thus provide a solid basis for functional studies of candidate centromere determining sequences.