G protein-coupled receptor 64 also known as HE6 is a protein encoded by the ADGRG2gene.[5] GPR64 is a member of the adhesion GPCR family.[6][7]
Adhesion GPCRs are characterized by an extended extracellular region often possessing N-terminal protein modules that is linked to a TM7 region via a domain known as the GPCR-Autoproteolysis INducing (GAIN) domain.[8][9]
The adhesion GPCR, GPR64, is an orphan receptor characterized by a long N-terminus with that has been suggested to be highly glycosylated.[10] GPR64's N-terminus has been reported to be cleaved at the GPS domain to allow for trafficking to the plasma membrane. After cleavage the N-terminus is believed to remain non-covalently associated with the 7TM. GPR64 expression has been mostly reported in the male reproductive organs, but more recently has been shown to be expressed in the parathyroid glands[11] and central nervous system.[12] GPR64 is mainly expressed in human and mouse epididymis as well as human prostate and parathyroid.[11][13] GPR64, together with F-actin scaffold, locates at the nonciliated principal cells of the proximal male excurrent duct epithelia, where reabsorption of testicular fluid and concentration of sperm takes place.[14][15]
^Stacey M, Yona S (2011). Adhesion-GPCRs: Structure to Function (Advances in Experimental Medicine and Biology). Berlin: Springer. ISBN978-1-4419-7912-4.
^Langenhan T, Aust G, Hamann J (May 2013). "Sticky signaling--adhesion class G protein-coupled receptors take the stage". Science Signaling. 6 (276): re3. doi:10.1126/scisignal.2003825. PMID23695165. S2CID6958640.
