Association of transglutaminase with the reconstituted keratin filaments isolated from rat vaginal epithelial cells.

We report a novel association of the calcium dependent cross-linking enzyme, transglutaminase (TGase) with the urea soluble reconstituted keratin filaments (RKF) isolated from the rat vaginal epithelial cells (VEC). This was ascertained by measuring the activity using 14C-spermidine incorporation and also by an increase in keratin filament aggregation by the addition of only TGase cofactor-calcium. These events were specifically inhibited by the treatment of calcium chelator, EDTA at a concentration > 2 mM as well as by pretreating the RKF with histamine, a TGase substrate inhibitor. The association was also exemplified by immunoblotting analysis where a specific and preferential polypeptide of molecular weight 58 kDa cross-reacted with TGase antibody amongst the other keratins. This phenomenon was not seen in the keratins isolated from skin, a non-targeting tissue for estradiol action.