Ionotropic Receptors

Ionotropic receptors (also known as ligand-gated channels) are large proteins thought to be composed of five subunits (other proteins) that assemble in the membrane. As suggested by their name, LGCs contain a neurotransmitter binding site and an intrinsic ion channel that is gated by the transmitter. This type of mechanism is therefore sometimes called ionotropic transmission.

Put plainly ionotropic receptors differ from a voltage-gated channel (i.e a door), because access is controlled by neurotransmitter binding (i.e lock & key) instead of the membrane potential reaching full threshhold (i.e. another lock & key) . Whether receptor activation depolarizes or hyperpolarizes the postsynaptic membrance depends on the ionic permeability of the channel.

Simplified model of ionotropic receptor

Location

Majority of ionotropic receptors are located along the dendrites or cell body.

Examples of receptors

Acetylcholine, nicotinic, glutmate on NMDA or GABA receptors. Futhermore there are receptor subtypes, the first identified are named the AMPA, kainate and NMDA. The aforementioned receptor subtypes are named after the agonists to which they respond selectively.

Sources

Feldman, R. S., Meyer, J. S., & Quenzer, L. F. (1997). Principles of neuropsychopharmacology. Sinauer Associates.

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