Identification of buccal mucosal mucin receptor.

A receptor for salivary mucin was isolated from epithelial cell membrane of buccal mucosa by a procedure involving membrane solubilization with octylglucoside followed by affinity chromatography on Sepharose-bound wheat germ agglutinin. The receptor protein displayed an apparent molecular weight of 97kDa and exhibited binding specific to mucin in a concentration-dependent manner. The receptor, furthermore, showed a requirement for carbohydrate chains in mucin for binding, as their removal caused a marked (89%) reduction in binding capacity. Scatchard analysis revealed a linear plot with a single class of high affinity binding (Kd = 1.1 microM; Bmax = 7.68nmol/mg protein. The results provide for the first time evidence for the existence in buccal mucosa of a specific receptor for salivary mucin.