Why do you need to “do” anything? Is there some reason you would like to see a monomer on your gels? It is common for membrane proteins to run as non-covalent oligomers in SDS-PAGE, and sometimes boiling makes it even worse. I think KCSA runs as a tetramer on gels, and several proteins I have worked with have never run exclusively (or at all!) as monomers, but often ran as ladders depending on conditions.
On the topic of unusual SDS-PAGE phenomena, it might be of general interest to point out that GFP and proteins tagged therewith remain fluorescent in SDS-PAGE gels unless they are boiled. And…RFP (mRuby2 in my case) seems to remain fluorescent even after boiling, although it shifts its apparent MW. And, well, two more: phosphorylation shifts apparent MW way more than the phosphate group’s mass, and calmodulin and other calcium-binding proteins shift a lot +/- calcium. There are of course explanations ex post facto, but I guess the general idea is that SDS-PAGE does not always work as the textbooks say. JPK From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of amit gaur Sent: Tuesday, February 21, 2017 5:23 PM To: [email protected] Subject: [ccp4bb] Dimer in SDS-PAGE Hi all, I am trying to purify a potassium ion channel from insect cell using baculovirus expression system. I am not seeing monomer of this protein in SDS instead a dimer appears.So,I increased DTT in SDS buffer but no change and dimer was intact. In size exclusion this protein appeared as a tetramer which is common oligomerizaton of potassium channel family with GYG motif. Can any body suggest what should I do in this case? Thanks and regards, -- Dr. Amit Gaur Post Doctoral Researcher PI: Dr. Ji-Fang Zhang Thomas Jefferson University 1020, Locust Street, Suite 418 Philadelphia, PA 19107
