so how to cleave off the GST? - (Oct/04/2006 )
Check out this handbook on GST (Not trying to market here)
I find it really useful. Hope it helps.
Do you have a plasmid map? If you can find it for the people who gave you the plasmid, you should be able to find the thrombin sequence. If it's really not there, I'm afraid you are going to have to do some more cloning work: either remove your protein, and put it into a plasmid that has a protease sequence, or try to introduce the sequence withing your plasmid.
How were the people who gave you the plasmid going to use their GST construct?