At high concentrations, free radicals and radical-derived, nonradical reactive species are hazardous for living organisms and damage all major cellular constituents. At moderate concentrations, how...

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Free Radicals in the Physiological Control of Cell Function

Protein kinase C, an enzyme that is activated by the receptor-mediated hydrolysis of inositol phospholipids, relays information in the form of a variety of extracellular signals across the membrane to regulate many Ca2+-dependent processes. At an early phase of cellular responses, the enzyme appears to have a dual effect, providing positive forward as well as negative feedback controls over various steps of its own and other signaling pathways, such as the receptors that are coupled to inositol phospholipid hydrolysis and those of some growth factors. In biological systems, a positive signal is frequently followed by immediate negative feedback regulation. Such a novel role of this protein kinase system seems to give a logical basis for clarifying the biochemical mechanism of signal transduction, and to add a new dimension essential to our understanding of cell-to-cell communication.

https://science.sciencemag.org/content/sci/233/4761/305.full.pdf

Studies and perspectives of protein kinase C

In recent years, members of the protein kinase family have been discovered at an accelerated pace. Most were first described, not through the traditional biochemical approach of protein purification and enzyme assay, but as putative protein kinase amino acid sequences deduced from the nucleotide sequences of molecularly cloned genes or complementary DNAs. Phylogenetic mapping of the conserved protein kinase catalytic domains can serve as a useful first step in the functional characterization of these newly identified family members.

http://science.sciencemag.org/content/sci/241/4861/42.full.pdf

The protein kinase family: conserved features and deduced phylogeny of the catalytic domains.

Hydrolysis of inositol phospholipids by phospholipase C is initiated by either receptor stimulation or opening of Ca2+ channels. This was once thought to be the sole mechanism to produce the diacylglycerol that links extracellular signals to intracellular events through activation of protein kinase C. It is becoming clear that agonist-induced hydrolysis of other membrane phospholipids, particularly choline phospholipids, by phospholipase D and phospholipase A2 may also take part in cell signaling. The products of hydrolysis of these phospholipids may enhance and prolong the activation of protein kinase C. Such prolonged activation of protein kinase C is essential for long-term cellular responses such as cell proliferation and differentiation.

https://science.sciencemag.org/content/sci/258/5082/607.full.pdf

Intracellular signaling by hydrolysis of phospholipids and activation of protein kinase C

Protein kinase C is now known to be a large family of proteins, with multiple subspecies that have subtle individual enzymological characteristics. Some members of the family exhibit distinct patterns of tissue expression and intracellular localization; different kinases probably have distinct functions in the processing and modulation of a variety of physiological and pathological responses to external signals.

The molecular heterogeneity of protein kinase C and its implications for cellular regulation

Quantitative measurement of sn-1,2-diacylglycerols present in platelets, hepatocytes, and ras- and sis-transformed normal rat kidney cells.

Cloning and expression of multiple protein kinase C cDNAs

Sphingomyelin turnover induced by vitamin D3 in HL-60 cells. Role in cell differentiation.

INTRODUCfION AND PERSPECfIVES ... ... 460 FATTY ACID ACTIVATION . . . . ..... . .. . . . . . . . . . . .. . .. . . . . . . . .. . .. .. . .. . 463 BIOSYNTHESIS OF PHOSPHATIDIC ACID .... ......... 464 Acylation of Glycerol-P • 464 Acylation of Lysophosphatidic Acid 465 Dihydroxyacetone-P Pathway 466 Diacylglycerol Kinase 467 BIOSYNTHESIS OF DIACYLGLYCEROL 468 BIOSYNTHESIS OF TRIACYLGL YCEROL ......... 469 BIOSYNTHESIS OF PHOSPHATIDYLCHOLINE AND . PHOSPHATIDYLETHANOLAMINE.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 470 Choline and Ethanolamine Kinases 470 Choline-P and Ethanolamine-P Cytidyltransferases 470 Cholineand Ethanoiaminephosphotransferases 471 Phosphatidylethanolamine N-methyltransferases 472 BIOSYNTHESIS OF CDP-DIACYLGL YCEROL AND THE ANIONIC PHOSPHOGLYCERIDES .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. ... . . . . . . 473 Biosynthesis of Phosphatidylglycerol and Cardiolipin 474 Biosynthesis of Phosphatidylinositol 474 Biosynthesis of bis-Monoacylglyc erol-P 474 PHOSPHOGLYCERIDE MODIFICATION REACfIONS 475 Base Exchange Reactions 475 Reacyiation Reactions 475

Robert M. Bell

Papers

Quantitative measurement of sn-1,2-diacylglycerols present in platelets, hepatocytes, and ras- and sis-transformed normal rat kidney cells.

Cloning and expression of multiple protein kinase C cDNAs

Sphingomyelin turnover induced by vitamin D3 in HL-60 cells. Role in cell differentiation.

Enzymes of glycerolipid synthesis in eukaryotes.

Lipid activation of protein kinase C.