Sandbox Reserved 1174: Difference between revisions

The LPA₁ receptor consists of seven transmembrane alpha helices. It lies in the membrane as shown in Figure 2, and as shown by the <scene name='72/721545/Membrane/6'>fatty acid</scene> bound in the crystallization of LPA₁ in orange. Most <scene name='72/721545/Polarity/4'>polar amino acids</scene> (red) reside on the intracellular and extracellular areas of the receptor, while most residues positioned on the trans membrane helices inside the membrane are hydrophobic (blue). A cytochrome b (b₅₆₂RIL) protein was inserted into the third intracellular loop to facilitate crystallization (Figure 2). The intracellular region of this membrane protein is coupled to a [https://www.ebi.ac.uk/interpro/potm/2004_10/Page2.htm heterotrimeric G protein].

Three native <scene name='72/721545/Disulfides/5'>disulfide bonds</scene> in the extracellular region of this receptor provide fold stability.<ref name= "Chrencik"/> The first disulfide bond constrains the N terminal helix to extracellular loop(ECL) 2. The second disulfide bond shapes ECL2, and the third binds ECL3 to one of the transmembrane alpha helices. These disulfide bonds provide intramolecular stabilization along the extracellular region of the LPA₁ receptor, where the substrate enters into the binding pocket. The <scene name='72/721545/N-terminus/3'>N-terminus</scene> is a six turn alpha helix. It functions like a cap on the extracellular side of the protein, packing tightly against ECL1 and ECL2. The N-terminus helix also provides <scene name='72/721545/34_39_40/4'>polar amino acids</scene> that interact with the ligand when bound. The extracellular region of this receptor plays a role in substrate specificity.