C-myc/anti-myc Ab Interaction with Fusion Proteins
After some further research, I found papers reporting successful co-immunoprecipitation experiments with POI-myc-His fusion proteins.

Moreover, I figured the signal sequence will be cleaved by signal peptidases which will leave the c-myc tag exposed on N-terminus with only an extra residue. I don't think that one extra residue will create a problem.

Here's the tool I used to figure out where the signal sequence will be cleaved:
http://www.cbs.dtu.dk/services/SignalP/

Here are the references for POI-myc-His experiments:


DOI: 10.1016/j.cub.2006.08.085
DOI: 10.1073/pnas.97.2.668