text: The G protein-coupled receptors have seven hydrophobic transmembrane domains.  Most of them are monomeric proteins, although GABA receptors require heterodimerization to function properly. The protein's N terminus is located on the extracellular side of the membrane and its C terminus is on the intracellular side.
  The 7 transmembrane spanning domains, with an external amino terminus, are often claimed as being alpha helix shaped, and the polypeptide chain is said to be composed of around 450&ndash;550 amino acids.