Hello Dr. Kay,

I suspect two possibilities here:

Case 1: If the protein is pure then this blot is a representative image of a heteromeric protein.

Case 2: If the purification process is incomplete then this low molecular weight protein band could be a protein interactive of your protein of interest.

Hopefully this helps you.

Best,

Sheethal Galande

PhD Research Fellow

AIG Hospitals

Protein-protein interaction*

Thanks Sheethal for your Answer.

To be clear, the bigger molecular weight band is my protein of interest ( my protein) and my question is about the small molecular weight band ( the 10kDa band).

I have repeated the production and the purificarion several times and I got this band with this protein !!