Sigma SAB2103628

Disclaimer: The fact that this page reports negative results with the given antibody does not mean that the antibody does not work – it just means that our laboratory did not succeed, using our typical experimental protocol, to find the searched protein by immunoblotting in the tissue examined. Modificiation of the protocol, or the selection of other tissue, might still provide excellent results.

In mouse liver microsomes, this puzzling antibody shows very nice and specific bands at about 75 kDa. The antibody is raised against the N-terminal domain of full-length (pro)matriptase-2, it should therefore detect the full length (pro)protein of approximately 125 kDa, and the residual N-terminal domain of about 95 kDa which probably remains bound to the hepatocyte plasma membrane once the full-length protein is activated by autocleavage (at arginine 576 in the mouse).

TMPRSS6 protein determination in liver microsomes from C57BL/6 mice  

10% gel, SAB 2102638 1:1000, various liver microsome samples.

The bands look really nice. However, there is one fundamental concern: Matriptase-2 is extensively glycosylated; following PNGase F treatment, the full-length protein loses 7 saccharides and, on immunoblots, shifts from approximately 125 kDa to approximately 90 kDa. All the sacchaides are located N-terminally of arginine 576, therefore, PNGase treatment should definitely significantly affect the observed 75 kDa band. Unfortunately, it does not, the size of the 75 kDa band does not change following PNGase treatment. In contrast, using the same samples, the Abcam ab56182 shows specific, glycosylated 125 kDa bands. Therefore, our interpretation must be that the very nice band detected by this antibody in vivo can  NOT be definitely confirmed as belonging to matriptase-2.