FIGURE 5.

Hif1p is present in a high molecular weight complex independent of HAT1 and HAT2 and influences an H3-specific HAT activity. A, whole cell extracts were resolved by Superose 6 chromatography and the elution of Hif1p and Hat2p was determined by Western blot analysis as indicated. The elution position of size standards is indicated above the fraction numbers. The whole cell extracts were derived from strains with the genotypes indicated on the right. The bottom panel shows the elution pattern of rHif1p isolated from Escherichia coli. B, Superose 6 column fractions from the indicated strains were assayed for histone acetyltransferase activity using free histones [³H]acetyl-CoA as substrates. Reaction products were resolved by 18% SDS-PAGE and processed for fluorography. Position of radiolabeled histones was visualized by exposure of x-ray film. Migration of histones H3 and H4, as determined by Coomassie Blue staining, is indicated.