PURIFICATION AND CHARACTERIZATION OF A PROTEIN-BINDING TO THE SP6 KAPPA-PROMOTER - A POTENTIAL ROLE FOR CARG-BOX BINDING FACTOR-A IN KAPPA-TRANSCRIPTION

A protein interacting with an AT-rich region that is a positive contro l element within the SP6 kappa promoter was purified and identified as CArG-box binding factor-A The purified protein was shown to interact specifically with the coding strand of single-stranded DNA and, with l ower affinity, with double-stranded DNA.A mutation that inhibited bind ing of the protein to the AT-rich region also aborted the transcriptio nal stimulatory effect of the region. Two Ets proteins, PU.1 and elf-1 , that have previously been shown to bind to an adjacent DNA element w ere shown to physically interact with CArG-box binding factor-A An ant iserum raised against the protein recognized two different forms indic ating either that different splice-forms of CArG-box binding factor-A are expressed, or that the protein is subject to post-translational mo dification.