EXPRESSION PROBLEM IN GST TAGGED PROTEIN - (May/20/2011 )

hi, i have a GST tagged clone in pGEX 4T vector. my protein size is 128kda and GST is 26kDa (approx). so finally total size is 154kDa approx. i am trying to express in BL21. i have tried at 24 and 28oC temp with 0.5mM, 1.0mM,3mM and 5mM IPTG conc. i dont find any difference in induced and uninduced samples. but when i pull down with GST beads i find a very high level of GST expression but my protein is not at all expressed. please suggest ..

Are you sure that you're expressing from the vector with an insert and not from an empty one?