I am using western blot to investigate the level of expression of the g protein, Gq, in cardiovascular, renal, and arterial tissues. I have been getting prominent bands at 42 kDa and 25 kDa. The molecular weight of Gq is 42 kDa so I am very confused as to why there is a prominent second band at 25 kDa. Is anyone aware of splice variants of Gq? I have used this same antibody for cell lysates and I only saw one band.
Dear Alethia,
Take into account that your protein of interest (Gq) is a hetero-trimeric G protein somatimes called "large G proteins", however, there are also smaller G proteins (20-25kDa) belonging to Ras superfamily (GTPases) which are homologous to alpha (α) subunit of heterotrimeric G proteins.
The question is: It might be possible that your lower MW band is because of this type of smaller G proteins? You may review and check the specificity of your antibody; you mentioned that you used it with cell lysates: what cell type or cell line? are those cells similar or related to the tissue types you are studying?
Also take into account that tissue extracts contain proteins from various cell types present in the tissue structure, and they are often very difficult to obtain extracts from a single cell type.
Hope my comments be of some use to you and I wish you good luck in your work.
Your first point is very interesting. I will look into that. The cell line that I used was HEK293.
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