In this chapter we try to show a comprehensive image of current knowledge of structure, activity and physiological role of the P2Y1 purinergic receptor. The structure, distribution and changes in the expression of this receptor are summarized, as well as the mechanism of its signaling activity by the intracellular calcium mobilization. We try to show the connection between the components of its G protein activation and cellular or physiological effects, starting from changes in protein phosphorylation patterns and ending with such remote effects as receptor-mediated apoptosis. The special emphasis is put on the role of the P2Y1 receptor in cancer cells and neuronal plasticity. We concentrate on the P2Y1 receptor, it is though impossible to completely abstract from other aspects of nucleotide signaling and cross-talk with other nucleotide receptors is here discussed. Especially, the balance between P2Y1 and P2Y12 receptors, sharing the same ligand but signaling through different pathways, is presented.
Keywords: Calcium signaling; Cancer cells; Neuronal plasticity; P2Y1 receptors; P2Y1/P2Y12 cross-talk.