Protein Domain : P2X6 purinoceptor IPR003049

Type	Family
Description	P2X purinoceptors are cell membrane ion channels, gated by adenosine 5'-triphosphate (ATP) and other nucleotides; they have been found to be widely expressed on mammalian cells, and, by means of their functional properties, can be differentiated into three sub-groups. The first group is almost equally well activated by ATP and its analogue alpha,betamethylene-ATP, whereas, the second group is not activated by the latter compound. A third type of receptor (also called P2Z) is distinguished by the fact that repeated or prolonged agonist application leads to the opening of much larger pores, allowing large molecules to traverse the cell membrane. This increased permeability rapidly leads to cell death, and lysis.Molecular cloning studies have identified seven P2X receptor subtypes, designated P2XR1-P2XR7, however, P2X1R, P2X2R, P2X3R, P2X4R, and P2X7R are functional [ ]. These receptors are proteins that share 35-48% amino acid identity, and possess two putative transmembrane (TM) domains, separated by a long (~270 residues) intervening sequence, which is thought to form an extracellular loop. Around 1/4 of the residues within the loop are invariant between the cloned subtypes, including 10 characteristic cysteines.Studies of the functional properties of heterologously expressed P2X receptors, together with the examination of their distribution in native tissues, suggests they likely occur as both homo- and hetero multimers in vivo [ , ]. Stimulation of these receptors induces changes in intracellular ion homeostasis leading to multiple key responses crucial for initiation, propagation, and resolution of inflammation []. The P2X7 subtype has an important role in the activation of lymphocyte, granulocyte, macrophage and dendritic cell responses and, therefor, it may be a promising target for anti-inflammatory therapies.The P2X6 receptor (along with P2X2, P2X4 and P2X5) falls into a group of receptors that are sensitive to ATP, but not alphabetamethyleneATP. There is some evidence that P2X6 may heteropolymerise with P2X4, since they are often found together in native tissues, and can be co-immunoprecipitated. P2X6 and P2X4 receptors are present in the gastrointestinal tract, being involved in synaptic transmission, taste sensation, and pain, among other functions. P2XR6 is present in capillary vessels in the proximal region of the gut and to a lesser extent in the distal region [ ].
Short Name	P2X6_purnocptor