. "Conveys a signal from an upstream receptor or intracellular signal transducer by catalysis of the reaction: ATP protein serine = ADP + protein serine phosphate, and ATP + protein threonine = ADP + protein threonine phosphate." . . . "receptor signaling protein serine/threonine kinase activity" . "receptor signalling protein serine/threonine kinase activity" . . . . . . . .