Purinergic receptors, also known as purinoceptors, are a family of plasma membrane molecules that are found in almost all mammalian tissues. Within the field of purinergic signalling, these receptors have been implicated in learning and memory, locomotor and feeding behavior, and sleep. More specifically, they are involved in several cellular functions, including proliferation and migration of neural stem cells, vascular reactivity, apoptosis and cytokine secretion. These functions have not been well characterized and the effect of the extracellular microenvironment on their function is also poorly understood.
The P2X receptors, also ATP-gated P2X receptor cation channel family, is a protein family that consists of cation-permeable ligand-gated ion channels that open in response to the binding of extracellular adenosine 5'-triphosphate (ATP). They belong to a larger family of receptors known as the ENaC/P2X superfamily. ENaC and P2X receptors have similar 3-D structures and are homologous. P2X receptors are present in a diverse array of organisms including humans, mouse, rat, rabbit, chicken, zebrafish, bullfrog, fluke, and amoeba.
β2-glycoprotein 1, also known as beta-2 glycoprotein 1 and Apolipoprotein H (Apo-H), is a 38 kDa multifunctional plasma protein that in humans is encoded by the APOH gene. One of its functions is to bind cardiolipin. When bound, the structure of cardiolipin and β2-GP1 both undergo large changes in structure. Within the structure of Apo-H is a stretch of positively charged amino acids, Lys-Asn-Lys-Glu-Lys-Lys, are involved in phospholipid binding.
Integrin beta-3 (β3) or CD61 is a protein that in humans is encoded by the ITGB3 gene. CD61 is a cluster of differentiation found on thrombocytes.
Integrin alpha-IIb is a protein that in humans is encoded by the ITGA2B gene. ITGA2B, also known as CD41, encodes integrin alpha chain 2b. Integrins are heterodimeric integral membrane proteins composed of an alpha chain and a beta chain. Alpha chain 2b undergoes post-translational cleavage to yield disulfide-linked light and heavy chains that join with beta 3 to form a fibrinogen receptor expressed in platelets that plays a crucial role in coagulation. Mutations that interfere with this role result in thrombasthenia. At least 38 disease-causing mutations in this gene have been discovered. In addition to adhesion, integrins are known to participate in cell-surface mediated signalling.
P2X purinoceptor 7 is a protein that in humans is encoded by the P2RX7 gene.
P2Y purinoceptor 1 is a protein that in humans is encoded by the P2RY1 gene.
P2Y purinoceptor 2 is a protein that in humans is encoded by the P2RY2 gene.
Protease activated receptor 3 (PAR-3) also known as coagulation factor II receptor-like 2 (F2RL2) and thrombin receptor-like 2, is a protein that in humans is encoded by the F2RL2 gene.
P2Y purinoceptor 6 is a protein that in humans is encoded by the P2RY6 gene.
P2Y purinoceptor 4 is a protein that in humans is encoded by the P2RY4 gene.
Glycoprotein IX (platelet) (GP9) also known as CD42a (Cluster of Differentiation 42a), is a human gene.
Glycoprotein V (platelet) (GP5) also known as CD42d (Cluster of Differentiation 42d), is a human gene.
Multimerin 1, also known as elastin microfibril interfacer 4 (EMILIN-4), is a protein that, in humans, is encoded by the MMRN1 gene.
P2X purinoceptor 4 is a protein that in humans is encoded by the P2RX4 gene. The product of this gene belongs to the family of purinoceptors for ATP. Multiple alternatively spliced transcript variants have been identified for this gene although their full-length natures have not been determined.
P2X purinoceptor 5 is a protein that in humans is encoded by the P2RX5 gene.
Scinderin is a protein that in humans is encoded by the SCIN gene. Scinderin is an actin severing protein belonging to the gelsolin superfamily. It was discovered in Dr. Trifaro's laboratory at the University of Ottawa, Canada. Secretory tissues are rich in scinderin. In these tissues scinderin, a calcium dependent protein, regulates cortical actin networks. Normally secretory vesicles are excluded from release sites on the plasma membrane by the presence of a cortical actin filament network. During cell stimulation, calcium channels open allowing calcium ions to enter the secretory cell. Increase in intracellular calcium activates scinderin with the consequent actin filament severing and local dissociation of actin filament networks. This allows the movement of secretory vesicles to release sites on the plasma membrane.
P2X purinoceptor 2 is a protein that in humans is encoded by the P2RX2 gene.
P2X purinoceptor 3 is a protein that in humans is encoded by the P2RX3 gene.
P2X purinoceptor 6 is a protein that in humans is encoded by the P2RX6 gene.
