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Acetylcholine muscarinic receptors?

Hi, so I'm aware of the sub-types: M1, m2 etc
but what is the significance of Gi and Gq receptors? Like what does this mean?

Reply 1

Helenia

Original post by MedStudentt

Hi, so I'm aware of the sub-types: M1, m2 etc
but what is the significance of Gi and Gq receptors? Like what does this mean?

It's the type of G protein they're coupled to, which mediates the intracellular effects of the receptor. IIRC, Gs stimulates adenylyl cyclase and increases cAMP production, Gi inhibits adenylyl cyclase (and reduces cAMP) and Gq stimulates phospholipase 3, which cleaves PIP2 into IP3 and DAG, both of which have further downstream effects.

Reply 2

thegodofgod

Original post by MedStudentt

Hi, so I'm aware of the sub-types: M1, m2 etc
but what is the significance of Gi and Gq receptors? Like what does this mean?

As above - cAMP and IP₃ are second messenger molecules, which have various roles, e.g. IP₃ binds to the IP₃ receptor, which activates ligand-gated Ca²⁺ ion channels, allowing ER stores of Ca²⁺ to be released into the cytoplasm and subsequently, smooth muscle contraction.