CHARACTERISTICS AND LOCALIZATION OF RAT SUBMANDIBULAR-GLAND PROTEOGLYCANS

The submandibular gland proteoglycans were investigated biochemically and immunohistochemically in male Sprague-Dawley rats. Proteoglycans w ere extracted with 4 M guanidine-HCl, followed by ultracentrifugation in a CsCl density gradient, and fractionated by ion-exchange chromatog raphy and gel filtration. The molecular weight of PGs was estimated by SDS-PAGE and immunoblot analysis with monoclonal antibodies (HepSS-1 or 6-B-6). The glycosaminoglycan sidechains in the proteoglycan fracti ons were identified by electrophoresis on cellulose acetate membrane. Three proteoglycan fractions were obtained. One was a heparan sulphate proteoglycan that migrated as a diffuse band of about 210 kDa. The ot her two fractions contained at least two dermatan sulphate proteoglyca ns of 70-85 kDa and 40-50 kDa. Digestion of these two proteoglycans wi th chondroitinase ABC, but not heparitinase, produced two bands of 50 and 21 kDa, which were core proteins. The smaller dermatan sulphate pr oteoglycan may be a portion of the other, as the core protein of both bound to 6-B-6 antibody, and sugar chains of both were the same (20-30 kDa). Heparan sulphates recognized by antibody HepSS-1 were observed widely in the basement membrane, fibrous connective tissue, and striat ed and excretory ductal cells, while dermatan sulphate proteoglycans r ecognized by antibody 6-B-6 were located in the connective tissue surr ounding striated and excretory ducts. Copyright (C) 1997 Elsevier Scie nce Ltd.