Inositol trisphosphate signal transduction

Carland, EM., and Nelson, T., 2004, COTYLDEDON VASCULAR PATTERN2-mediated Inositol (1,4,5) trisphosphate signal transduction is essential for closed venation patterns of Arabidopsis foliar organs. Plant Cell 16 1263-1275. 

Figure 1. Simplified schematic of receptor-mediated signal transduction in neutrophils. Binding of ligand to the receptor activates a guanine-nucleotide-binding protein (G protein), which then stimulates phospholipase C. Phosphatidylinositol 4,5-bis-phosphate is cleaved to produce diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). DAG stimulates protein kinase C. IP3 causes the release of Ca from intracellular stores, which results in an increase in the cytosolic Ca concentration. This increase in Ca may stimulate protein kinase C, calmodulin-dependent protein kinases, and phospholipase A2. Protein phosphorylation events are thought to be important in stimulating degranulation and oxidant production. In addition, ionic fluxes occur across the plasma membrane. It is possible that phospholipase A2 and ionic channels may be governed by G protein interactions. ...

Fig. 12. Tentative model of the signal transduction chain that links the perception of pectic fragments to defense responses in carrot cells. Abbreviations apy, heterotrimeric G protein CaM, calmodulin 4CL, 4-coumarate-CoA ligase CTX, cholera toxin FC, fusicoccine GDP-P-S and GTP-y-S, guanosine 5 -0-(2-thiodiphosphate) and guanosine 5 -0-(3-thiotriphosphate) IP3, 1,4,5-inositol trisphosphate PAL, phenylalanine ammonia-lyase PLC, phospholipase C PR, pathogenesis related PTX, pertussis toxin Rc, receptor SP, staurosporine. Activation and inhibition are symbolized by + and -respectively.

Sugawara H, Kurosaki M, Takata M, Kurosaki T 1997 Genetic evidence for involvement of type 1, type 2 and type 3 inositol 1,4,5-trisphosphate receptors in signal transduction through the B-cell antigen receptor. EMBO J 16 3078-3088... 

Somlyo AP, Somlyo AV 2000 Signal transduction by G-proteins, Rho-kinase and protein phosphatase to smooth muscle and non-muscle myosin II. J Physiol 522 177—185 Somlyo AP, Devine CE, Somlyo AV, N orth SR 1971 Sarcoplasmicreticulumand the temperature-dependent contraction of smooth muscle in calcium-free solutions. J Cell Biol 51 722—741 Somlyo AP, Walker JW, Goldman YE et al 1988 Inositol trisphosphate, calcium and muscle contraction. Philos Trans R Soc Lond B Biol Sci 320 399 114 Somlyo AP, Wu X, Walker LA, Somlyo AV 1999 Pharmacomechanical coupling the role of calcium, G-proteins, kinases and phosphatases. Rev Physiol Biochem Pharmacol 134 201-234... 

Berridge, M. J., Irvine, R. F. (1984). Inositol trisphosphate, a novel second messenger in cellular signal transduction. Nature 312, 315-21. 

Rosales, C., Brown, E. J. (1992). Signal transduction by neutrophil immunoglobulin G Fc receptors. Dissociation on intracytoplasmic calcium concentration rise from inositol 1,4,5-trisphosphate. J. Biol. Chem. 267, 5265-71. 

The signal transduction mechanisms triggered by binding of ET-1 to its vascular receptors include stimulation of phospholipase C, formation of inositol trisphosphate, and release of calcium from the endoplasmic reticulum, which results in vasoconstriction. Conversely, stimulation of PGI2 and nitric oxide synthesis results in decreased intracellular calcium concentration and vasodilation. 

Fadool, D. A. and Ache, B. W., Plasma membrane inositol 1,4,5-trisphosphate-activated channels mediate signal transduction in lobster olfactory receptor neurons, Neuron, 9, 907, 1992. 

The opposing effects on smooth muscle (A) of a- and p-adrenoceptor activation are due to differences in signal transduction, ai -Receptor stimulation leads to intracellular release of Ca2+ via activation of the inositol trisphosphate (IP3) pathway. In concert with the protein calmodulin, Ca2+ can activate myosin kinase, leading to a rise in tonus via phosphorylation of the contractile protein myosin (— vasoconstriction). 012-Adrenoceptors can also elicit a contraction of smooth muscle cells by activating phospholipase C (PLC) via the py-subunits of G, proteins. 

Likewise, phosphatidyl inositol is formed by the transfer of a diacylglycerol phosphate unit from CDP-diacylglycerol to inositol. Subsequent phosphorylations catalyzed by specific kinases lead to the synthesis of phosphatidyl inositol 4,5-bisphosphate, an important molecule in signal transduction. Recall that hormonal and sensory stimuli activate phospholipase C, an enzyme that hydrolyzes this phospholipid to form two intracellular messengers—diacylglycerol and inositol 1,4,5-trisphosphate (Section 15.2). 

Figure 8-5. Signal transduction involving Ca2+ and the phosphatidyiinosito bisphosphate (PIP2) system. DAG = diacylglycerol IP3 = inositol 1,4,5-trisphosphate G = G proteins = stimulates.

Fig. 2 The bitter taste signal transduction cascade. Bitter taste receptors are G-protein-coupled receptors. Activation of TAS2Rs results in the activation of the heterotrimeric G-protein complex a-gustducin (a-gust), 3 or pi, and yl3. The Py-subunits activate phospholipase C P2, (PLCj52) resulting in the production of inositol 1,4,5-trisphosphate (/P3). The IP3-mediated increase of intracellular calcium activates transient receptor potential channel 5 (TRPM5)...

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