How do you optimize your PCR condition? I have met the same thing. I use KOD to amplify my target gene. I only got the small fragment. Later I increased the denature and primer annealing time (from 20s to 25s). Interestingly, the bigger band appeared.
in fact, i haven't solve this question yet, i want to do northern-blot, your suggestion maybe work, i will try it, thanks!
the big problem of AS is how to study the function, especially the different function to wild type gene, do you have any good idea?