Protein Extraction and Centrifugation - (Nov/02/2008 )

Hi!I am a student and got an novel assignment on novel/chaperon proteins recently which was pretty confusing and vague. I was supposed to extract novel liver cancer cell line HepG2 and to purify and characterise it with the requirements on to find out whether the synthesis of the protein is localised in the cell by using protein extraction and centrifugation.
I dont really know where to start from cause there are so many methods regarding both extraction and isolation so it would be really helpful if you could give me tips on the protocol of this protein.
Oh ya its located in the cytoplasm and 213kD with 3 subunits amd pI 7 which i have no idea particular idea on what it means.Suggestions and hints would be hugely appreciately cause im really dumbfounded with this assignment
Thanks alot mate!

wow, plan on doing anything before asking for help?