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. 2013 Jan 17;3(1):14–28.

Figure 1.

Figure 1

Type 2 purinergic receptors and their nucleotide agonists. Extracellular nucleotides bind to type 2 purinergic receptors exerting their effects on cells’ function. Two distinct P2 receptor subfamilies were described P2X and P2Y. P2X receptors are membrane cation channels gated exclusively by extracellular ATP. Seven P2X receptors have been cloned and named P2X1-7. They are oligomers of three subunits each composed by an extracellular loop, two transmembrane domains and an amino- and a carboxyl-terminal both cytoplasmic. ATP binding induce the subunits assembly to form omo- or etero-multimerc channels permeable to monovalent and divalent cations. P2Y receptors are seven membrane-spanning, G-protein-coupled receptors. Eight P2Y subtype receptors have been cloned so far named P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, P2Y12, P2Y13 and P2Y14. They can be subdivided into adenine nucleotide-preferring receptors (P2Y1, P2Y11, P2Y12 and P2Y13), uracil nucleotide-preferring receptors (P2Y4 and P2Y6), a receptor of mixed specificity (P2Y2) and a UDP-glucose-preferring receptor (P2Y14).