SIGNALING MECHANISMS THAT REGULATE SALIVA FORMATION

The precipitating event in the formation of saliva is the binding of n eurotransmitter molecules to cell surface receptor proteins. The princ ipal neurotransmitters involved are acetylcholine and norepinephrine t hat bind. respectively, to muscarinic-cholinergic, and alpha- and beta -adrenergic receptors. The transduction of the extracellular signal re quires an integral membrane protein capable of binding GTP, a G protei n, that specifically interacts with the receptor. The components of G protein transduction systems are fairly well studied, but the pathways by which signals are routed are just being recognized. Delineation of such routing pathways is essential to understanding the regulation of saliva formation.