GENOMIC LOCALIZATION OF THE HUMAN GENE ENCODING DR1, A NEGATIVE MODULATOR OF TRANSCRIPTION OF CLASS-II AND CLASS-III GENES

Dr1 is a nuclear protein of 19 kDa that exists in the nucleoplasm as a homotetramer. By binding to TBP (the DNA-binding subunit of TFIID, an d also a subunit of SL1 and TFIIIB), the protein blocks class II and c lass III preinitiation complex assembly, thus repressing the activity of the corresponding promoters. Since transcription of class I genes i s unaffected by Drl, it has been proposed that the protein may coordin ate the expression of class I, class II and class III genes. By somati c cell genetics and fluorescence in situ hybridization, we have locali zed the gene (DR1), present in the genome of higher eukaryotes as a si ngle copy, to human chromosome region 1p21 --> p13. The nucleotide seq uence conservation of the coding segment of the gene, as determined by Noah's ark blot analysis, and its ubiquitous transcription suggest th at Drl has an important biological role,which could be related to the negative control of cell proliferation.