RAT SUBMANDIBULAR AND PAROTID PROTEIN-PHOSPHORYLATION AND EXOCYTOSIS - EFFECT OF SITE-SELECTIVE CAMP ANALOGS

A series of cAMP analogs that have different specificities for the two different binding sites on the regulatory subunit of type I and type II cAMP-dependent protein kinase (PKA) were used to determine whether selective activation of type I or type II PKA could link either or bot h isozyme forms of PKA with exocytosis and specific protein phosphoryl ation in salivary gland cells. Using dispersed rat submandibular or pa rotid cells, selective activation of either type I or type II resulted in a synergistic response for both rat submandibular mucin and paroti d amylase secretion and the phosphorylation of a 26-kDa integral membr ane phosphoprotein. These data suggest that the activation of either i sozyme of PKA can elicit cellular exocytosis and specific protein phos phorylation in both of these cell types.