P3 receptors

Metabolic effects. P-Receptors mediate increased conversion of glycogen to glucose (glycogenolysis) in both liver and skeletal muscle. From the liver, glucose is released into the blood. In adipose tissue, triglycerides are hydrolyzed to fatty acids lipolysis, mediated by P3-receptors), which then enter the blood (C). The metabolic effects of catecholamines are not amenable to therapeutic use. 

Molecular genetic techniques have confirmed the existence of multiple subtypes of p-adrenoceptors. Pi-Receptors and Pj-receptors have been cloned, and recent molecular biological evidence indicates the existence of at least one additional p-receptor sub-type, called the p3-receptor. It is suggested that the P3-receptor may mediate some of the metabolic effects of catecholamines, although no available p-blocker has been shown to rely on Pa-receptor antagonism for its therapeutic effectiveness. 

Synder and colleagues purified and reconstituted the inositol- 1,3,4-P3 receptor. 

P-Adrenoceptors are best known for their role in the regulation of cardiovascular, airway, uterine, and peripheral metabolic functions. Mice lacking pj, p2 and p3 receptors have been generated (Chruscinski et al. 1999 Rohrer et al. 1996 Susulic et al. 1995), but only few studies have used these models to identify subtype-specific functions of P-adrenoceptors in neurons. 

Arch defines the P3-receptor using pharmacological criteria... 

The preparation of inositol and structurally related phosphates continues to be actively explored. Examples include the first total synthesis of the inositol tetraphosphate enantiomeric pair, Ins(l,2,3,4)P4 (27) and Ins(l,2,3,6)P4 (28). Compounds (27) and (28) were dephosphorylated by a number of different enzymes and thus provide routes to specific inositol triphosphates. A number of myo-inositol 1,4,5-triphosphates, e.g. (29)-(32), modified at the 6-position have been prepared. All such derivatives investigated showed poor affinity for Ins(l,4,5)P3 receptors. A new and comparatively convenient synthesis of I-d-6-0-(2-amino-2-deoxy-a-D-glycopyranosyl)-chiro-inositol 1-phosphate (33) and the corresponding 1,2-cyclic phosphate (34) has been reported. The first examples of poly(ethylene glycol)-linked dimers (35) of D-myo-inositol 1,4,5-triphosphate have been prepared as probes for multi-subunit binding proteins for... 

Santella L, Ercolano E, Lim D, Nusco GA, Moccia F. 2003. Activated M-phase-promoting factor (MPF) is exported from the nucleus of starfish oocytes to increase the sensitivity of the Ins(l,4,5)P3 receptors. Biochem Soc Trans 31(Pt l) 79-82. 

C H2 N50,8P3 669.325 Prod, by Penicillium brevicompactum. Calcium channel activator. Activates inositol triphosphate (Ins(l,4,5)P3) receptor. Sol. H2O, DMSO fairly sol. MeOH, EtOH poorly sol. Mc2CO, CHCI3, EtOAc. Mg +28.6 (c, 0.7 in H2O). 

ER Scheme 3.11). Reports indicate that the Ins(l,4,5)P3 receptors (InsP3R) are intracellular channel proteins that mediate the release of Ca from ER and regulate a number of processes such as cell proliferation and death. 

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