NRSC 2100 1st Edition Lecture 10 Neurotransmitter receptors I Receptors are transmitter gated proteins II Together with neurotransmitters receptors work in a Lock and Key arrangement III There have been 100 s of receptors isolated that respond to a variety of chemical neurotransmitters IV Several receptor proteins can bind the same neurotransmitter ex ACh binds both nicotinic and muscarinic receptors V Studying Receptor Subtypes e g ACh receptors Nicotinic Muscarinic Glutamate receptors AMPA NMDA kainate and mGluRs Major Categories of Receptors Ionotropic receptors transmitter gated ion channels Fast synaptic transmission Sensitive detectors of chemicals and voltage Directly regulate flow of ionic currents Differentiate between similar ions Amino Acid Gated Channels Glutamate Gated Channels AMPA NMDA kainate These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Amino Acid Gated Channels GABA Gated and Glycine Gated Channels Both mediate fast inhibitory synaptic transmission Glycine receptors spinal cord GABA brain Metabotropic receptors G protein coupled receptors Multiple steps mediating signaling Binding of the neurotransmitter to the receptor protein Activation of G proteins homomeric and trimeric forms Exchange of GDP to GTP on alpha subunit Activation of effector systems The Basic Structure of G Protein Coupled Receptors GPCR Single polypeptide with seven membrane spanning regions Activation of G proteins exchange of GDP to GTP dissociation of and subunits can lead to several intracellular effects 1 Direct binding to ion channels e g free subunits bind and open K channels action of Ach in heart 2 Binding of subunit to effector proteins and production of secondmessengers e g binding to adenylate cyclase increases cAMP concentrations 3 Activation or inhibition of second messengers induce further changes mediating modulation of metabolic activity channel functions gene expression Actions of metabotropic receptors are usually much slower than ionotropic receptors 10s of msec to minutes of longer durations extensively amplified compared to ionotropic receptor actions A Few More Categories of Receptors 3 Enzyme linked receptors e g tropomyosin receptor kinase trk Toll like receptors TLRs they activate a variety of intracellular signaling pathways Intracellular receptors often hormone receptors that respond to lipophilic chemicals that can cross lipid membranes relatively freely often translocate to the nuclei and work as transcription factors RECEPTOR LOCATION Post synaptic receptors Pre synaptic receptors Heteroreceptors respond to NT other than the ones contained in its synaptic vesicles Autoreceptors respond to NT that are released from it s own synaptic vesicles usually inhibitory