G protein

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G Protein

G protein (pronounced /ˈdʒiː ˈproʊtiːn/), also known as guanine nucleotide-binding proteins, are a family of proteins involved in transmitting chemical signals outside of a cell, and causing changes inside the cell. They are called 'G proteins' because they bind to guanine nucleotides.

Etymology

The term "G protein" comes from the ability of these proteins to bind to guanine nucleotides. The "G" stands for guanine, one of the four nucleobases in the nucleic acids DNA and RNA.

Function

G proteins are involved in transmitting signals from a variety of stimuli outside a cell to its interior. They are activated by G protein-coupled receptors (GPCRs) that span the cell membrane. When a ligand binds to a GPCR, it causes a conformational change in the GPCR, which allows it to act as a guanine nucleotide exchange factor (GEF). The GPCR can then activate an associated G protein by exchanging the GDP bound to the G protein for a GTP.

Types

There are four main types of G proteins, which are classified based on their function and the type of GPCR with which they interact. These are Gs (stimulatory), Gi (inhibitory), Gq, and G12/13.

Related Terms

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