GST Fusion Proteins in Yeast

[Bill Brickey]

      We have constucted and apparently expresssed a fusion protein
with GST at the end terminus and a yeast ORF of unknown function at the
C terminus.  After induction, we can detect a  fusion protein of the
right size using polyclonal anti-GST anti-body.  The size of the fusion
protein is 60-70kDa.  However, following standard protocols we cannot
get the protein to stick to Glutathione Sepharose.  
      1. Is there something in yeast extracts which interferes with
         binding?  Are there alternate protocols ?