NEUR 201: Receptors

What are receptors?

[ proteins that are capable of sending a signal to change the function or activity of a neuron. ] transmembrane proteins, ligands bind to the part of the receptor on the extracellular side. receptors are specific for their ligand NT

Ligand

signaling molecule, at a NT, or drug

Types of postsynaptic receptors

1. Ligand-gated ion channels (iontropic)

2. G-protein-coupled receptors (metabotropic)

Ionotropic receptors

aka ligand-gated on channel receptors. ONLY ions pass through. induces a change in membrane potential (EPSP or IPSP)

Metabotropic Receptors (GPCRs)

act SLOWER than ligand-gated ion channel receptors, produces a modulatory signal. spans the membrane 7 times. signal cascade inside the neuron instead of letting ions through.

[GPCR] What is the receptor linked to on the intracellular side?

G-protein

Different types of G-Proteins

alpha and gamma

What energy does GPCR use?

GTP

What is GTP used for?

movement

When the NT binds, what gets exchanged?

GDP for GTP

Alpha subunit’s role:

detaches with GTP attached and will start a signaling cascade

Beta and Gamma subunit’s role:

stick together and either stay attached to the membrane or activate a different subunit

Metabotropic Receptors (alpha subunits)

Gas, Gai, Gaq

What does Gas do?

s is for stimulatory — these receptors increase activity of an enzyme called adenylyl cyclase, cyclic AMP, and PKA

What does Gai do?

i is for inhibitory — these receptors decrease activity

What does Gaq do?

generally excitatory, activates different enzymes compared to Gas

Autoreceptors

on occasion, a NT my have receptors on the presynaptic side (on the membrane of the axon terminal)

Autoreceptors function

inhibitory and serve a self-regulatory function. can often decrease or increase NT release from that axon terminal