DUAL LOCALIZATION OF THE HUMAN GENE ENCODING HNRNP I PTB PROTEIN TO CHROMOSOMES 19P13.3 AND 14Q23/

A cDNA probe representative of the human hnRNP I/PTB gene was used to perform fluorescence in situ hybridization (FISH) on metaphases of hum an chromosomes. A new localization was found on band 19p13.3 in additi on to the previously reported localization to band 14q23. Identical re sults were obtained when FISH analysis was repeated with probes coveri ng different parts of the hnRNP I cDNA clone. This supported the notio n that most, if not all, of the sequences of the different parts of th is clone are present on both chromosomes. Moreover, Southern blot anal ysis of DNAs from interspecies somatic hybrids containing chromosomes 19 and 14 revealed that the whole hnRNP I cDNA probe generated very si milar patterns in each hybrid DNA. These data suggest that two closely related copies of the hnRNP I gene exist in the human genome.