My work is to confirm which part of a gene is interact with another gene. So I built up five fragment constructs in p3XFlag-CMV-7.1 vectors and transfected in 293T cells. Four out of five constructs expressed well--very strong and even signals with Flag-HRP IB with correct sizes. But one fragment did not show anything. I double checked the sequence and did not find any problem. The bone frame and technique to build up these five constructs are all the same but only this one won't express. Anyone has the same problem?
Any suggestion will be greatly appreciated!