CHARACTERIZATION OF THE PROPERTIES OF A HUMAN HOMOLOG OF ESCHERICHIA-COLI RECQ FROM XERODERMA-PIGMENTOSUM GROUP-C AND FROM HELA-CELLS

We showed that DNA-dependent ATPase Q1 (DNA helicase Q1) from xeroderm a pigmentosum complementation group C (XP-C) cells elutes from FPLC Mo no Q column at higher concentrations of KCI than that from other human cells (35), We purified DNA helicase Q1 from XP-C and HeLa cells, The purified fractions of both cells contained a major polypeptide with a molecular mass of 73 kDa and had the same enzymatic properties, inclu ding salt- and temperature-sensitivity. Characterization using an anti -DNA helicase Q1 antibody indicated that this enzyme localized in the nuclei and was not modified by incorporating phosphate groups through phosphorylation and ADP-ribosylation, No interactions of DNA helicase Q1 with other proteins were indicated by immunoprecipitation of the he licase from crude extracts, No difference was observed in XP-C cells i n intracellular localization of DNA helicase Q1, phosphorylation, and the interaction with other proteins as compared to HeLa cells.