text: The GPCR superfamily is the largest gene family in the human genome containing approximately 800 genes. As the vertebrate superfamily can be phylogenetically grouped into five main families, the GRAFS classification system has been proposed, which includes the glutamate, rhodopsin, adhesion, Frizzled/Taste2, and secretin GPCR families.
  There are 33 human adhesion GPCRs that can be broken down into eight groups, with two independent receptors.  Group I consists of LPHN1, LPHN2, LPHN3, and ETL.  Group II consists of CD97, EMR1, EMR2, EMR3, and EMR4.  Group III consists of GPR123, GPR124, and GPR125.  Group IV consists of CELSR1, CELSR2, and CELSR3.  Group V consists of GPR133 and GPR144.  Group VI consists of GPR110, GPR111, GPR113, GPR115, and GPR116.  Group VII consists of BAI1, BAI2, and BAI3.  Group VIII consists of GPR56, GPR97, GPR112, GPR114, GPR126, and GPR64.  Two additional adhesion GPCRs do not fit into these groups: VLGR1 and GPR128.