Characteristics of cell-membrane and extracellular proteoglycans in monkey submandibular gland

We investigated the characteristics of cell-membrane and extracellular proteoglycans in the monkey submandibular gland using enzymatic digestion and Western blot analysis. Extracellular proteoglycans and cell-membrane proteoglycans were extracted from the phosphate-buffered saline (PBS) soluble fraction and microsomal fraction of submandibular glands, respectively, and purified partially by ion exchange chromatography. Cellulose acetate membrane electrophoresis and immunoblotting with 3G10 monoclonal antibody or 6B6 monoclonal antibody showed that the extracellular proteoglycans contain several heparan sulfate proteoglycans (117, 67, 47 and 35 kDa core proteins) and a dermatan sulfate proteoglycan (45-50 kDa core protein), while the cell-membrane proteoglycans contain only a heparan sulfate proteoglycan with 69 kDa core protein. These results indicate that the several extracellular heparan sulfate proteoglycans may be released ectodomains of the cell-membrane proteoglycans from cell surface. It is suggested that the cell-membrane and extracellular proteoglycans may regulate the function of growth factors and the microenvironment in the normal submandibular gland.