protein dimerisation - how do I determine if it is? (Feb/20/2005 )

I have been seeing a very strong band on a western blot at double the expected size of my protein, but only from my cell lysates - not from mouse tissues (I do use trizol protein extraction from tissues and homogenise, compared with a buffer of (boiling hot) tris, vanadate, sds, and potease inhibitors for my cells). We are wondering if this is a dimer of my protein.

How do I go about determining whether or not my protein dimerises? Are there specific experiments I can perform?

Thanks

Dtermine the mol wt of the native protein by gel filtration chromatography and then by SDS PAGE. The latter gives the wight of the monomeric form , while the former infdicates that of non-denatured form. The ration of difference gives the no. of homomeric subunits preseent.

Good Luck

Sharath.B
Research Fellow
National Chemical Laboratory
India