Reiteration frequency mapping: analysis of repetitive sequence organization within cloned DNA fragments containing the human initiator methionine tRNA gene.

The organization of repetitive sequences within three cloned chromosomal segments from human fetal liver DNA containing the initiator methionine tRNA gene was studied. The procedure developed for this study involves the contact hybridization of an electrophoretically separated 5'-32P-labeled restriction endonuclease digest of the cloned segment with total human genomic DNA covalently bound to aminobenzyloxymethyl-paper. The extent of hybridization of each labeled fragment to the area of paper with which it is in contact is proportional to the representation of the sequence within the human genome. We show that sequences with a wide range of genomic repetitition are present in the neighborhoods of the three dispersed initiator tRNA loci, each characterized by a different overall organization pattern.