Mechanism of action of ANP is through-

Ans. is 'b' i.e., cGMP Enzyme linked receptorsa) Intrinsic enzyme receptors (tyrosine kinase receptors)# These type of receptors have an extracellular domain for attachment of hormone and an intracellular (cytoplasmic domain) that has enzymatic activity, i.e. tyrosine kinase.# The characteristic feature of these receptors is that hormone binding induces dimerization of receptor molecule.# After binding of hormone, tyrosine kinase autophosphorylates tyrosine residue of dimer itself as well as phosphorylates other substrate proteins which then perform specific function.# Examples - Insulin, epidermal growth factor (EGF), PDGF, FGF.b) JAK-STAT-Kinase binding receptors# These receptors differ in not having intracellular enzymatic action on receptor itself. Agonist binding induces interaction of these receptors with free intracellular tyrosine kinase - Janus kinase (JAK).# JAK phosphorylates the activators of transcription (STAT), which then regulate the nucleus transcription resulting in a biological response.# Examples - Growth hormone, Prolactin.c) Guanylyl cyclase (GC)# Activation of GC results in increased synthesis and intracellular accumulation of cGMP. cGMP acts through cGMP dependent protein kinase.# Hormone acting through cGMP are atrial natriuretic peptide and nitric oxide