Serpentine receptors are a large family of cell-surface receptors that are coupled to heterotrimeric G proteins. They are also known as G protein-coupled receptors (GPCRs). Serpentine receptors are found in all animals, and they play a variety of roles in cellular signaling, including regulating hormone levels, the release of neurotransmitters, and the contraction of muscles.

The name "serpentine" comes from the characteristic serpentine shape of these receptors. They have a seven-transmembrane domain, which is a series of seven helical regions that span the cell membrane. The extracellular loops between these domains form the binding site for the ligand, while the intracellular loops interact with the G protein.

When a ligand binds to a serpentine receptor, it causes a conformational change in the receptor that activates the G protein. This leads to a series of downstream signaling events that can result in a variety of cellular responses, such as the release of neurotransmitters or the contraction of muscles.

Serpentine receptors are a very important family of receptors, and they are involved in a wide variety of cellular signaling processes. They are also the target of many drugs, including those used to treat asthma, heart disease, and depression.