LOCALIZATION OF FCGR1 ENCODING FC-GAMMA RECEPTOR CLASS-I IN PRIMATES - MOLECULAR EVIDENCE FOR 2 PERICENTRIC INVERSIONS DURING THE EVOLUTIONOF HUMAN-CHROMOSOME-1

The human high-affinity receptor for immunoglobulin G, Fc gamma RI (FC GR1), is encoded by a family of three genes that share over 95% sequen ce homology. Curiously, the three genes in this recently duplicated ge ne family flank the centromere of human chromosome 1, with FCGR1B loca ted at 1p12 and both FCGR1A and FCGR1C located at 1q21. We have previo usly speculated that a pericentric inversion could account for the sep aration of the genes in the FCGTS1 family and explain their current ch romosomal location. Here we present evidence, obtained through fluores cence in situ hybridization analysis, that in the rhesus monkey (Macac a mulatta) and baboon (Papio papio) FCGR1 is located adjacent to the c entromere on the chromosomal arm with greatest homology to human 1p, w hereas in the chimpanzee (Pan troglodytes) it is located adjacent to t he centromere on the chromosomal arm with greatest homology to human 1 q. The separation of the FCGR1 gene family in humans suggests that the location of a second pericentric inversion, known to distinguish the human from the chimpanzee chromosome 1, is within the FCCR1 gene famil y. This finding refines the assignment of homology between the human a nd chimpanzee chromosomes 1.