a) Lithium stimulates ACTH secretion by anterior pituitary cells in culture. Lithium, phorbol esters, high extracellular calcium, and diacylglycerol comprise a distinct class of agents affecting ACTH secretion through mechanisms involving phospholipases, inositide metabolism, and protein kinase C. b) The enzyme which transfers long chain fatty acids from acyl coenzyme A to rhodopsin has been solubilized and partially purified. This reaction is prototypical of a new class of posttranslational modification of membrane proteins, including receptors.
