I've been trying to express a V5 epitope tagged 7TM protein in a cell line. I am able to see that the gene of interest is being overexpressed by real-time PCR. However, in a western blot, I see a V5 band running about 100kDa higher than expected size. I feel like the protein may not be migrating through the gel. After reading through this board it appears that I should not have boiled my samples and there may be some other tips. I'm just wondering if anyone has a reference or general protocol for properly preparing GPCR proteins for western blots. Thanks.