With Anti-xCT antibody (ab37185), I have obtained ever time the two separate bands composed of 55kDa and 37kDa. Many papers insist that 37kDa is the correct one, but as far as si-RNA-mediated depletion of xCT resulted in the loss of both bands, I think 55kDa-sized xCT band is also important. xCT is well known to bind to CD98 (heavy chain), but if so, the MW shift is expected to be more dramatic.
Dear Go you do not mention which type of sample you are analyzing.
Anyways the MW in the data sheet of Ab37185 indicates 55 kDa as the right MW for human and mouse.
What 37 comes from? perhaps the theoretical size according to the sequence of amino acids??
The samples were obtained from embryonic mouse firboblasts (MEF), SV40 antigen-transfected immortalized MEF, HRAS G12V)-transfected MEF, 4T1 murine breast cancer cells, and PANC1 human pancreatic cancer cells, all of which showed the same pattern of xCT WB bands.
Is there any possibility that 37kDa-sized bad comes from the cleavage of the full length of xCT???
First of all I think that it is good that you only detect two bands. The 37 KDa one may be nonspecific but it specific (as I bet) there are a couple of options:
- xCT has glycosylation sites but this wouild lead to higher and not lower MW.
- I do not favour that the 37 one is the "good" one and the 55 comes after glycosylated one.
- If glycosylation is not the answer truncation (proteolytic cleavage) may happen. If so clean (just one cut) I bet it is physiological and not the result of poteolysis during isolation.
- Alternative splicing may be another possibility.
- If proteolysis or alternative splicing the antibody used will help you in knowing that the missing part in the 37 KDa band is not the N-terminal one. The Ab you use detects this string: MVRKPVVSTI SKGGYLQGNV NGRLPSLGNK EPPGQEKVQL (N terminal intracellular)
- Badges
- Science topic
- Similar topics
- Biological Science
- Immunology
- Antibodies