Expression synthases

If noncyclic photosynthetic electron transport leads to the translocation of 3 H /e and cyclic photosynthetic electron transport leads to the translocation of 2 H /A, what is the relative photosynthetic efficiency of ATP synthesis (expressed as the number of photons absorbed per ATP synthesized) for noncyclic versus cyclic photophosphorylation (Assume that the CFiCEq ATP synthase yields 1 ATP/3 H. )... 

Fatty acid synthesis 1 SREBP-1c, HNF-4a l Expression ACC1, fatty acid synthase Liver... 

Increased lipid synthesis/inhibi-tion of lipolysis Activation of lipoprotein lipase (LPL)/induc-tion of fatty acid synthase (FAS)/inactivation of hormone sensitive lipase (HSL) Facilitated uptake of fatty acids by LPL-dependent hydrolysis of triacylglycerol from circulating lipoproteins. Increased lipid synthesis through Akt-mediated FAS-expression. Inhibition of lipolysis by preventing cAMP-dependent activation of HSL (insulin-dependent activation of phosphodiesterases )... 

Kleinert H, Pautz A, Linker K, Schwarz PM (2004) Regulation of the expression of inducible nitric oxide synthase. Eur J Pharmacol 500 255-266... 

Neuronal NO synthase (nNOS) is constitutively expressed in neurons of the brain. Its activity is regulated by Ca2+ and calmodulin. Half-saturating L-arginine concentrations are around 2 pM. cDNAs encoding nNOS have been cloned from rat and human brain. The open reading frame of human nNOS consists of 4299 bp, corresponding to 1433 aa. This predicts a protein of 160 kDa, which is in accordance with the molecular mass of the purified protein. 

Inducible NO synthase (iNOS) is usually not constitutively expressed, but can be induced in macrophages by bacterial lipopolysaccharide (LPS), cytokines and other-agents. Although primarily identified in macrophages, expression of the enzyme can be stimulated in virtually any cell or tissue, provided the appropriate inducing agents have been identified (for review see [1] and [3]). 

Endothelial NO Synthase (eNOS) expression is relatively specific for endothelial cells. However, the isozyme has also been detected in certain neurons of the brain, in syncytiotrophoblasts of human placenta and in LLC-PKi kidney tubular epithelial cells. 

Forstermann U (2000) Regulation of nitric oxide synthase expression and activity. In Mayer B (ed) Handbook of experimental pharmacology — nitric oxide, vol. 143. Springer, Berlin, pp 71—91... 

Kleinert H, Boissel J-P, Schwarz PM et al (2000) Regulation of the expression of nitric oxide synthases. In Ignarro LJ (ed) Nitric oxide, biology and pathobiology. Academic Press, San Diego, CA, pp 105-128... 

Phospholipase D is widely distributed in bacteria, fungi, plants and animals, and is present in almost all mammalian cells [3]. In mammals, it occurs as alternatively spliced products of two genes (PLD1 andPLD2) (Fig. 3). Most mammalian cells express different levels of both isoforms. Both PLD1 and PLD2 have four conserved sequences (I-IV), and sequences I and IV contain the HXKX4D (HKD) motif that is characteristic of the PLD superfamily, which includes bacterial endonucleases, phospholipid synthases, viral envelope... 

Schaefer U, Schneider A, Rixen D, Neugebauer E (1998) Neutrophil adhesion to histamine stimulated cultured endothelial cells is primarily mediated via activation of phospholipase C and nitric oxide synthase isozymes. Inflamm Res 47(6) 256-264 Schaefer U, Schmitz V, Schneider A, Neugebauer E (1999) Histamine induced homologous and heterologous regulation of histamine receptor subtype mRNA expression in cultured endothelial ceUs. Shock 12(4) 309-315... 

Han HS, Qiao Y, Karabiyikoglu M, Giffard RG, Yenari MA. Influence of mild hypothermia on inducible nitric oxide synthase expression and reactive nitrogen production in experimental stroke and inflammation. J Neurosci 2002 22 3921-3928. 

Clearly, the control of gene expression at the transcriptional level is a key regulatory mechanism controlling carotenogenesis in vivo. However, post-transcriptional regulation of carotenoid biosynthesis enzymes has been found in chromoplasts of the daffodil. The enzymes phytoene synthase (PSY) and phytoene desaturase (PDS) are inactive in the soluble fraction of the plastid, but are active when membrane-bound (Al-Babili et al, 1996 Schledz et al, 1996). The presence of inactive proteins indicates that a post-translational regulation mechanism is present and is linked to the redox state of the membrane-bound electron acceptors. In addition, substrate specificity of the P- and e-lycopene cyclases may control the proportions of the p, P and P, e carotenoids in plants (Cunningham et al, 1996). 

POTRYKUS I (1997) Transgenic rice Oryza sativa) endosperm expressing daffodil Narcissuspseudonarcissus) phytoene synthase accumulates phytoene, a key intermediate of provitamin A biosynthesis , Plant J, 11, 1071-78. 

FRASER P D, ROMER S, SHIPTON C A, MILLS P B, KIANO I W, MISAWA N, DRAKE R G, SCHUCH W and BRAMLEY p M (2002) Evaluation of transgenic tomato plants expressing an additional phytoene synthase in a fruit-specific manner , Proc Natl Acad Sci, 99, 1092-7. 

FRAY R, WALLACE A, FRASER P D, VALERO D, HEDDEN P, BRAMLEY P M and GRIERSON D (1995) Constitutive expression of a fruit phytoene synthase gene in transgenic tomatoes causes dwarfism by redirecting metabolites from the gibberellin pathway . Plant J, 8, 696-701. 

Expression of a tomato cDNA coding for phytoene synthase in Escherichia coli, ph)doene formation in vivo and in vitro, and functional analysis of the varions trimcated gene prodncts , J Biochem (Tokyo), 116, 980-85. 

SCHLEDZ M, AL-BABILI S, VON LINTIG J, HAUBRUCK H, RABBANI S, KLEINIG H and BEYER P (1996) Phytoene synthase fcom Narcissus pseudonarcissus functional expression, galactolipid requirement, topological distribution in chromoplasts and induction during flowering . Plant J, 10, 781-92. 

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