Briefly describe the PIP₂ signaling Depletion of PIP₂ = Increase excitiability = Closes M-channels (K⁺) = Decrease M-current	By activating G_q coupled receptors, we can signal by (3): 1. Depletion of PIP₂ in the membrane 2. Liberation of IP₃ and hence intracellular Ca²⁺ release 3. Liberation of DAG and hence activation of PKC	Describe G-protein coupled receptors and give an example Transduce effect in seconds Critical for neuronal function G_s and G_i acting on adenylyl cyclase (ATP-> cAMP) that activate PKA G_q acting on phospholipase C to degrade PIP₂ into DAG and IP₃ that in turn activate PKC Eg) GABA_B, muscarinic ACh, histamine receptors
Describe kinase-linked receptors and give an example Kinase phosphorylates Transduce effect in hours Critical for hormonal function Eg. Insulin, growth factors, insulin Eg. receptor Tyrosine Kinase	Describe ligand-gated ion channels and give an example Transduce effect in milliseconds Critical for neuronal function AMPA and NMDA receptors (glutamate) GABA_A receptor Nicotinic ACh receptor	Describe nuclear receptors and give an example Transduce effect in hours Critical for steroid hormone function Eg. Cortisol, thyroid hormone
How does PKA get activated? Cyclic AMP (cAMP) derived from ATP by adenylyl cyclase activates PKA