P2X2 purinoceptor (IPR003045)
Short name: P2X2_purnocptor
Overlapping homologous superfamilies
- P2X purinoreceptor (IPR001429)
- P2X2 purinoceptor (IPR003045)
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 P2X1-P2X7. 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 heteromultimers in vivo [PMID: 10414359, PMID: 12270951].
P2X2 receptors (which have been found to be alternatively spliced), are half-maximally activated by a concentration of ATP of ~10 micromolar. In contrast, alphabetamethyleneATP is found to be largely ineffective. This agonist profile has been found to be shared by the P2X4, P2X5 and P2X6 receptors. The single-channel properties of the P2X2 receptor are quite similar to those noted for the native receptor present on PC12 cells [PMID: 10414359].
- PR01309 (P2X2RECEPTOR)