Ca2+- and calmodulin-dependent protein phosphorylation in rat lacrimal gland.

Ca2+, in homogenized lacrimal glands, enhanced phosphorylation of several peptides. Phosphorylation of two of these peptides was further stimulated by addition of the Ca2+-binding protein calmodulin and decreased by trifluoperazine, an inhibitor of Ca2+--calmodulin-dependent activity. Thus, Ca2+--calmodulin-dependent protein kinases and their substrates are present in lacrimal gland and could have an important role in lacrimal-gland function.