<prompt> All are second messengers EXCEPT?cAMPDAGIP3Guanylyl cyclase  <response>: Ans. D Guanylyl cyclaseRef: Gattong, 25 ed. pg. 59 Guanylyl cyclase is an enzyme that catalyses the formation of cGMP. cGMP is important for vision in both rods and cones. Second messengers bring about short term changes by altering enzyme function, triggering exocytosis and can also lead to alteration of transcription of various genes Examples of secondary messengers cAMP: Produced by action of adenyl cyclase enzyme and stimulates protein kinase A which catalyses phosphorylation of proteins and altering there activity. For example cholera toxin increases cAMP levels whereas pertussis toxin inhibits it. IP3: Inositol phosphate diffuses into endoplasmic reticulum and triggers calcium release. DAG: Diacyglycerol works with IP3. 