DIFFERENT LOCALIZATIONS OF 21-KDA AND 27-KDA GAP-JUNCTION PROTEINS INRAT SALIVARY-GLANDS

Antibodies against 21 and 27 kDa gap-junction proteins from rat liver were used to examine the identification and localization of gap-juncti on proteins in rat salivary glands. Acinar cells of the submandibular glands and parotid glands stained well for the 27 kDa gap junction pro tein and less intensely for the 21 kDa protein. Acinar cells of the su blingual glands were stained heavily for the 27 kDa gap junction prote in and stained well for 21 kDa gap junction protein. No 27 kDa protein was observed in the ducts of the salivary glands. The 21 kDa gap-junc tion protein was distributed in some of the intercalated ducts in the parotid and submandibular glands. Immunoblotting of an extract of paro tid glands with antibodies against 21 and 27 kDa gap-junction proteins revealed the presence of 21 and 27 kDa proteins in the parotid glands . It is concluded that the 27 kDa gap-junction protein is distributed as a major component of the gap junctions in the acinar cells of all t he salivary glands; the 21 kDa protein is localized as a minor compone nt in the acinar cells and some portions of the intercalated ducts in the salivary glands. It is possible that these gap-junction proteins m ight contribute to the regulation of function of the salivary glands.