Purinergic P2Y12 Receptor/HORK3

Other Nomenclature:  Q9H244; ADP-glucose receptor; ADPG-R; Platelet ADP receptor,HORK3, SP1999.

Purine nucleotide receptor are classified in to two classes, the ionotrophic ligand-gated channels, P2X and the metabotropic G-protein coupled receptors, P2Y (1).  There are 7 P2X receptors and 11 P2Y (P2Y1-2, 4, 6 and 11-14) each with unique agonist response profile has been identified.  The subtypes of metabotropic receptors P2Y1 and P2Y2 are predominantly expressed in arterinal smooth muscle.  P2Y receptors are G protein-coupled receptors (GPCRs) activated by nucleotides, such as ATP, ADP, UTP, UDP, or UDPglucose, depending on the receptor subtype. Currently, 8 subtypes are known including P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, P2Y12, P2Y13, and P2Y14.  P2Y receptors play an important role in osteoclastic resorption and ATP and UTP are inhibitors of bone formation in osteoblasts. Activation of P2 receptors in bone cells not only involves the propagation of intercellular calcium waves but also the proliferation and activity of the cells (2).   Some of these receptors tend to associate with each other to make heterodimers.   ADP is an endogenous agonist for both P2Y1 and P2Y12 on platelets, and antagonism of its action at P2Y1 or P2Y12 receptor has been shown to inhibit platelet aggregation.  Adenine nucleotide anatagonist, INS50589, binds to P2Y12 and has been used clinically in acute coronary syndrome patients. 

P2Y12 is a G-protein coupled receptor characterized of presence of 7TMD.  The P2Y12 is negatively coupled via Gi to adenylate cyclase. Upon activation it inhibits the adenylyl cyclase second messenger system. Stimulation of P2 receptor releases a number of factor of inflammatory mediators like IL-1b, IL-1a, IL-6, IL-8 and TNFalpha (2).   The P2Y12-receptor plays a crucial role in ADP-induced platelet aggregation. Both the P2Y1 and P2Y12 receptors contribute to platelet P-selectin exposure, interactions of platelets with leukocytes and exposure of tissue factor on activated leukocytes, which should translate into a direct role of these receptors in atherosclerosis (2).The P2Y12 is highly expressed in platelets, lower levels are reported in brain and lowest levels are detected in lung, appendix, pituitary and adrenal glands.  The P2Y12 is also expressed in spinal cord and fetal brain.  P2Y12 receptor when expressed in host cells showed significant heterogeneity on SDS-PAGE mobility like many other PGCRs.   The P2Y12 is a 342 aa protein with characteristic 7TMDs of GPCR, exhibit a broad band od 52-60kDa.   The P2Y12R sequence analyses suggest the presence of putative N-glycosylation sites near the extra cellular N-terminal end of the proteins.  The protein has a large 3^rd intra cellular loop which interacts with G-proteins and has several phosphorylation sites.

 The P2Y12R-selective antibodies were generated against conserved but unique sequences on from P2Y12 protein form near C-terminal end form within 320-342 aa.  The peptide sequence was conserved in human, monkey and some other species.  The P2Y12R antibodies were affinity purified on an immobilized antigen based affinity chromatography.  These epitope-specific antibodies strongly labeled P2Y12 protein in P2Y12-western blot positive controls.  Anti-P2Y12-selective antibodies are also available as fluorescent conjugates for direct application in IHC.  FabGennix, Inc., will also provide Western blot positive controls for most of these antibodies in ready-to-use buffer for easy identification of respective proteins.  Limited quantities of antigenic peptides are also available.  Please enquire for their availability before ordering. FabGennix Int. Inc. also provides antibodies against several other GPCRs including many orphan receptors, for a complete listing visit www.fabgennix.com.  

For research use only, not for diagnostic or therapeutic use.