CHROMOSOMAL LOCALIZATION AND CDNA CLONING OF THE GENES (DDB1 AND DDB2) FOR THE P127 AND P48 SUBUNITS OF A HUMAN DAMAGE-SPECIFIC DNA-BINDINGPROTEIN

DDB is a damage-specific DNA binding protein whose binding activity is absent from a minority of cell strains from individuals with xeroderm a pigmentosum Group E, a human hereditary disease characterized by def ective nucleotide excision DNA repair and an increased incidence of sk in cancer. The binding activity from HeLa cells is associated with pol ypeptides of M(r) 124,000 and 41,000 as determined by SDS-polyacrylami de gels. This report describes the isolation of full-length human cDNA s encoding each polypeptide of DDB. The predicted peptide molecular ma sses based on open reading frames are 127,000 and 48,000, When express ed in an in vitro rabbit reticulocyte system, the p48 subunit migrates with an M(r) of 41 kDa on SDS-polyacrylamide gels, similarly to the p eptide purified from HeLa cells. There is no significant homology betw een the derived p48 peptide sequence and any proteins in current datab ases, and the derived peptide sequence of p127 has homology only with the monkey DDB p127 (98% nucleotide identity and only one conserved am ino acid substitution). Using a fluorescence in situ hybridization tec hnique, the DDB p127 locus (DDB1) was assigned to the chromosomal loca tion 11q12-q13, and the DDB p48 locus (DDB2) to 11p11-p12. (C) 1995 Ac ademic Press,Inc.