2 NONHISTONE PROTEINS ARE ASSOCIATED WITH THE PROMOTER REGION AND HISTONE HI WITH THE TRANSCRIBED REGION OF ACTIVE HSP-70 GENES AS REVEALED BY UV-INDUCED DNA-PROTEIN CROSS-LINKING INVIVO

We described here an approach for mapping proteins on any sequence of genomic DNA. UV-induced DNA-protein crosslinking within whole cells and the 'protein image' hybridization technique (1) were applied to test the proteins bound to different regions of the D.melanogaster hsp-70 gene. The histone H1-DNA association with the coding region is shown to be maintained, even during very intensive transcription, but is absent in the promoter. Two non-histone proteins with apparent molecular masses of 50 kD (p50) and 100 kD (p100) are crosslinked only to the active hsp-70 gene regulatory region and preferentially bind to its complementary and coding DNA strands, respectively.