Describe g protein coupled receptors that inhibit adenylyl cyclase in detail?

G protein-coupled receptors (GPCRs) that inhibit adenylyl cyclase are a type of cell surface receptor that are involved in signal transduction pathways. These receptors are coupled to inhibitory G proteins, specifically the Gαi subunit, which is responsible for inhibiting adenylyl cyclase activity.

When a ligand binds to the GPCR, it causes a conformational change in the receptor that activates the associated G protein. The Gαi subunit then dissociates from the Gβγ subunit and inhibits adenylyl cyclase activity by directly binding to the enzyme. Adenylyl cyclase is responsible for converting ATP into cyclic AMP (cAMP), a second messenger that plays a key role in intracellular signaling pathways.

By inhibiting adenylyl cyclase, GPCRs that are coupled to Gαi proteins decrease the production of cAMP in the cell. This leads to a decrease in the activation of protein kinase A (PKA), a downstream effector of cAMP signaling. As a result, various cellular processes that are regulated by PKA, such as gene expression, metabolism, and cell growth, are inhibited.

Overall, GPCRs that inhibit adenylyl cyclase play a crucial role in regulating cellular responses to extracellular signals and maintaining homeostasis in the body. These receptors are involved in a wide range of physiological processes and are potential targets for drug development in the treatment of various diseases.