DEFINITION OF A NEW ALPHA-SATELLITE SUPRACHROMOSOMAL FAMILY CHARACTERIZED BY MONOMERIC ORGANIZATION

We have analyzed more than 500 alphoid monomers either sequenced in ou r laboratory or available in the literature. Most of them belonged to the well studied suprachromosomal families 1, 2 and 3 characterized by dimeric (1 and 2) and pentameric (3) ancestral periodicities. The seq uences that did not belong to the previously known families were subje cted to further analysis. About a half of them formed a relatively hom ogenous family. Its members were on average 80.5% identical and 89.5% homologous to the Ml consensus sequence derived from this group (39 mo nomers). In the genome they do not form any ancestral periodicities ot her than a monomeric one, and are found at least in chromosomes 13, 14 , 15, 21, 22 and Y. The newly defined family was termed suprachromosom al family 4. Comparison of all 10 alphoid monomeric groups identified so far showed that the Ml sequence is closely related to the J1-D2-W4- W5 homology grouping. Notably the African Green Monkey alpha satellite , also characterized by monomeric construction, appears to be a member of the same group.