Biochemically active human DNA repair protein, xeroderma pigmentosum G
(XPG), was overexpressed in insect cells by a recombinant baculovirus
. The recombinant baculovirus produced XPG with a mobility of similar
to 185 kDa in a denaturing polyacrylamide gel. Indirect immunofluoresc
ence studies demonstrated that the recombinant full-length XPG protein
was expressed predominantly as a nuclear protein. The recombinant XPG
protein was purified to apparent homogeneity using Q-sepharose, S-300
size exclusion, and Mono Q column chromatography. XPG protein showed
a structure-specific DNA endonuclease activity, and a preferential aff
inity to single-stranded DNA and RNA compared to double-stranded DNA.