I'm going to detect protein-protein interaction with BiFC assays and my target proteins are ER retention with KDEL motif. so I want to fuse VC to the N-terminal of my protein. My question is if the VC is on the N-terminal, Can I add a HA tag to the N-terminal of VC155? If there is a tag, the tag is linked directly with the N-terminal of VC155 or there should be a linker between tag and VC155? thank you.