Two different types of receptor proteins

BIO3411- Discussion #6TA; Hyungjin KimTwo different types of receptor proteins(1) Ionotropic or ligand-gated ion channels- rapid postsynaptic effects- PSP arises within a msec and lasts for only a few tens of msec or less- Ex. nAchR, Glu R or GABA R at CNS(2) Metabotropic or G-protein coupled receptors- much slower response- multiple proteins bind to each other sequentially (effector molecule and 2 ndmessenger)- Ex. mAchR, GABA R, Neuropeptide REffector pathway; ex. β-adrenergic receptorNeurotransmitters1) Small molecule neurotransmitters- Acetylcholine; Nicotinic receptor (Ionotropic), Muscarinic receptor (metabotropic;heart, smooth muscle)Sarin (inhibit Acetylcholinesterase)- Glutamate; Nearly all excitatory neurons in CNS are glutamatergicNMDA, AMPA, kainite receptorsAll of the ionotropic GluR are nonselective cation ion channelsMetabotropic gluR; inhibition of postsynaptic Ca and Na channels- GABA; GABAa, GABAc; ionotropic, inhibitory and permeable to ClGABAb; metabotropic, inhibitory by activation of K ch or blocking Cachannel (hyperpolarization)- Glycine; ligand-gated Cl channels2) Neuropeptides; encoded by genes, peptide processing (pre-propeptide, propeptide)ex. Substance P, opoid peptides (endorphins)Virtually all neuropeptides initiate their effects by activating G-protein coupled R.

BIO3411- Discussion #6TA; Hyungjin KimImportant points for preparing examsEquilibrium potential; point at electrical potential = chemical potential (Nernstequations)Resting potential; selective permeabilityAction potential generationThreshold, overshoot, inactivation, undershoot, refractory periodBulk concentration does not change.I = g x (V m -E ion )