ISOLATION OF A CDNA-ENCODING A UV-DAMAGED DNA-BINDING FACTOR DEFECTIVE IN XERODERMA-PIGMENTOSUM GROUP-E CELLS

XPE binding factor (XPE-BF) is deficient in a subset of patients from xeroderma pigmentosum complementation group E. Binding activity copuri fies with a 125 kDa polypeptide (p125) that binds to DNA damaged by ul traviolet (UV) radiation and many other agents. We isolated cDNA encod ing a polypeptide with a predicted amino acid sequence that matched th e sequences of eleven tryptic peptides derived from digestion of XPE-B F purified from human placenta. In vitro transcription and translation of the cDNA yielded a polypeptide of 125 kDa that bound specifically to UV-damaged DNA. Therefore the cDNA encodes either all or the major component of XPE-BF.