Reciprocal control

Briere F, de Waal Malefyt R, Liu YJ Reciprocal control of T-helper cell and dendritic cell differentiation. Science 1999 283 1183-1186. 

YAMAGISHI T, OTSUKA E and HAGIWARA H (2001) Reciprocal control of expression of mRNAs for osteoclast differentiation factor and OPG in osteogenic stromal cells by genistein evidence for the involvement of topoisomerase 11 in osteoclastogenesis. Endocrinol 142, 3632-7. 

Figure 3.13 Reciprocal control of PC and PDH complex (compare with Figure 3.1)...

Clearly, it would not be advantageous for synthesis and degradation to occur simultaneously, especially as they occur in the same cell compartment, the cytosol. Reciprocal control, that is when one enzyme is On the other is Off, is achieved via reversible phosphorylation of the key controlling enzyme and allosteric control (see Table 6.2 and Section 3.2.2). However, it is probable that both enzymes retain some residual activity at most times. 

Glycogen phosphorylase isoenzymes have been isolated from liver, brain and skeletal muscle. All forms are subject to covalent control with conversion of the inactive forms (GP-b) to the active forms (GP-a) by phosphorylation on specific serine residues. This phosphorylation step, mediated by the enzyme phosphorylase kinase, is initiated by glucagon stimulation of the hepatocyte. Indeed, the same cAMP cascade which inhibits glycogen synthesis simultaneously stimulates glycogenolysis, giving us an excellent example of reciprocal control. 

Figure 6.40 Reciprocal control of glycogen phosphorylase and glycogen synthase...

Figure 13.4 illustrates three aspects of the basal ganglia network. First, a reciprocal control exists between GPe and STN. Second the SNc acts not only on the striatum but also on the cortex, the STN and the GPi. Finally the location of the STN at the intersection between vertical and horizontal feedback loops is crucial. Reference [50] concludes that the BG can no longer be considered as a unidirectional linear system that transfers information based solely on a firing-rate code and must rather be seen as a highly organized network with operational characteristics that simulate a nonlinear dynamical system (Fig. 13.4). 

Hail DJ, Rouaoult TA, Tang CK, Chin J, Harford JB, Klausner RD (1992) Reciprocal control of RNA-binding and aconitase activity in the regulation of the iron-responsive element binding protein role of the iron-sulfur cluster. Proc Natl Acad Sci USA 89 7536-7540... 

Very little inter-plant transfer of or occurred from pea to barley in non-mycorrhizal systems with either intact plants or where the pea plants had their shoots removed. In mycorrhizal systems, significantly greater transfer occurred from decapitated pea plants (Fig. 3.4b). Whilst an elegant demonstration of such source sink relationships, this experimental design also suffered from the lack of reciprocal controls. Furthermore, an alternative mechanism for all such inter-plant transfer may simply be a more efficient uptake of elements liberated from donor plant roots by exudation or sloughing, by mycorrhizas associated with the receivers that are simply in the vicinity of the donor rhizosphere. None of the large number of inter-plant experiments reported actually discriminate between these alternative mechanisms. 

Complex organ control— the eye The eye contains multiple tissues with various functions, several of them under autonomic control (Figure 6-5). The pupil, discussed above, is under reciprocal control by the SANS (via alpha receptors) and the PANS (via muscarinic receptors) acting on two different muscles in the iris. The ciliary muscle, which controls accommodation, is under primary control of muscarinic receptors innervated by the PANS, with insignificant contributions from the SANS. The ciliary epithelium, on the other hand, has important beta receptors that have a permissive effect on aqueous humor secretion. 

How does control of key enzymes control carbohydrate metabolism Glycogen synthase and glycogen phosphorylase are reciprocally controlled by phosphoryla-... 

Byar DP (1990) Factorial and reciprocal control designs. Statistics in Medicine 9 55-63 discns-sion 63-54. 

Phosphorylation should increase the activity of enzyme 2 and decrease the activity of enzyme f. That being the case, an increase in intracellular cAMP levels could greatly increase the steady-state ratio of [B]/[A]. Such coordinated, reciprocal control of opposing metabolic sequences is observed frequently in cells. 

Discuss the different modes of regulation of acetyl CoA carboxylase. Explain the reciprocal control of fatty acid synthesis and degradation through global and local regulation and dietary composition. 

Hypoxia exerts a reciprocal control on transcription of glycolytic (increase) and mitochondrial (decrease) enzymes in myotubes (Webster et al. 1990). The effects on glycolytic enzymes may be mediated by the oxygen sensitive transcription factor HIE (hypoxia-inducible factor). In the immorta-Used mouse skeletal muscle cell line (C2C12), when used at low concentrations, azide inhibited more than 70 % of cytochrome oxidase activity without changes in bioenergetics (either lactate production or creatine phosphorylation) or mRNA for mitochondrial enzymes (Leary etal. 1998). 

Reciprocal Control of Cell Proliferation and Cell Death 22... 

Glycogen synthase, like phosphorylase, exists in both an active and a relatively inactive form and, like phosphorylase, is subject to phosphorylation/dephosphorylation. Glycogen synthesis and breakdown are reciprocally controlled and the many different hormones and neuronal... 

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