A PROCESSED J CHAIN PSEUDOGENE ON HUMAN-CHROMOSOME-8 THAT IS SHARED BY SEVERAL PRIMATE SPECIES

Human DNA contains two sequences that hybridize to a human J chain gen e probe: the J chain gene itself and a second previously uncharacteriz ed sequence. By cloning and sequence analysis we now show this related sequence to be a processed pseudogene, which we have localized using somatic hybrids to chromosome 8 (distinct from the functional gene on chromosome 4) and mapped by linkage analysis to 8q13-q21. The pseudoge ne provides evidence of an additional DNA insertion event as it contai ns an AluI element embedded in sequence corresponding to the 3' untran slated region of the gene. The extent of sequence divergence between t he pseudogene and the functional J chain gene suggests that the pseudo gene was created roughly 40-50 million years ago; consistent with this estimate, Southern blots suggest that the pseudogene is shared by gre at apes as well as Old World monkeys.