Fig. 1.

HPCF-dependent ³²P-radiolabeling of a nuclear protein. The cytosolic or nuclear fraction (5 mg/mL) of HeLa cells were incubated with [³²P-adenylate] NAD (50 mM) for 15 min at 25 °C in the absence (-) or presence (+) of HPCF (100 μg/mL). (A) The samples were resolved by SDS/PAGE, and radiolabeled bands were visualized by phosphorimaging of the dried gels. (B) ³²P-radiolabel incorporated into TCA precipitable material from cytosolic or nuclear fractions was quantified by scintillation counting. The data are presented as the fold-³²P-radiolabel incorporated over background (cell lysate fractions in the absence of HPCF Statistical significance was calculated for differences in ³²P-incorporation between samples containing HPCF and controls lacking HPCF.