P2X4 purinoceptor (IPR003047)
Short name: P2X4_purnocptor
Overlapping homologous superfamilies
- P2X purinoreceptor (IPR001429)
- P2X4 purinoceptor (IPR003047)
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].
The P2X4 receptor (along with P2X2, P2X5 and P2X6) falls into a group of receptors that are sensitive to ATP, but not alphabetamethyleneATP. There is some evidence that P2X4 may heteropolymerise with P2X6, since they are often found together in native tissues, and can be co-immunoprecipitated. Splice variants of the P2X4 receptor have been detected [PMID: 10414359].
- PR01311 (P2X4RECEPTOR)