PHYSICAL MAPPING OF SEQUENCES HOMOLOGOUS TO AN ENDOGENOUS RETROVIRUS LTR ON HUMAN-CHROMOSOME-19

The human genome contains multiple copies of sequences related to the HERV-K family of endogenous retroviruses, homologous to the B-type mou se mammary tumour virus. A DNA fragment closely resembling an HERV-K l ong tandem repeat (LTR) was detected in a library of hncDNA clones enr iched for sequences from human chromosome 19. Sites showing homology t o the sequence of this fragment have been identified on human chromoso me 19 by hybridization to previously mapped chromosome 19 cosmids. Thu s the distribution of LTR sequences on a specific human chromosome has been mapped for the first time. We estimate the total number of such sites on human chromosome 19 to be at least 110. Many of these sites a re located in the vicinity of known genes. The precise localizations ( to specific cosmids) of LTR-homologous sequences on chromosome 19 can serve as a reference source and will automatically provide further ins ight into LTR-gene relationships as new genes are mapped onto the chro mosome.