Universal Drinfeld-Sokolov Reduction and Matrices of Complex Size

We construct affinization of the algebra $gl_{\lambda}$ of ``complex size'' matrices, that contains the algebras $\hat{gl_n}$ for integral values of the parameter. The Drinfeld--Sokolov Hamiltonian reduction of the algebra $\hat{gl_{\lambda}}$ results in the quadratic Gelfand--Dickey structure on the Poisson--Lie group of all pseudodifferential operators of fractional order. This construction is extended to the simultaneous deformation of orthogonal and simplectic algebras that produces self-adjoint operators, and it has a counterpart for the Toda lattices with fractional number of particles.Comment: 29 pages, no figure

Protein phosphorylation in isolated mitochondria and the effects of protein kinase C

AbstractWhen isolated intact rat liver mitochondria are incubated with [γ-32P]ATP the major phosphorylated proteins are those of 47 and 36 kDa. Phosphorylation of the 47 kDa protein, but not of the 36 kDa protein, is inhibited by carboxyatractyloside, an inhibitor of mitochondrial ATP uptake, while phosphorylation of the 36 kDa protein is inhibited by various uncouplers and an inhibitor of mitochondrial respiration. Addition of purified protein kinase C to the isolated mitochondria leads to the phosphorylation of 69, 37 and 17 kDa proteins. As with other substrates for protein kinase C, phosphorylation of these proteins is dependent on Ca2+ and markedly stimulated by various tumor promoters

Inhibition of protein kinase C by tamoxifen

The antiestrogen drug tamoxifen inhibits rat brain protein kinase C in vitro, whether the enzyme is activated by Ca2+ and phospholipid (50% inhibitory dose, 100 microM), 12-O-tetradecanoylphorbol-13-acetate and phospholipid (50% inhibitory dose, 40 microM), or teleocidin and phospholipid. Tamoxifen does not inhibit the Ca2+- and phospholipid-independent phosphorylation of protamine sulfate by protein kinase C, indicating that the drug does not interact with the active site of the enzyme. The binding of [3H]phorbol dibutyrate to high-affinity membrane receptors of cultured mouse fibroblast cells is inhibited by tamoxifen (50% inhibitory dose, 5 microM). Our findings suggest that the growth-inhibitory and cytotoxic effects of tamoxifen, which have been observed at microM concentrations of the drug, may be in part due to its effects on protein kinase C

Triphenylethylenes: a new class of protein kinase C inhibitors

The Ca2+- and phospholipid-dependent phosphotransferase activity of protein kinase C was inhibited by the triphenylethylene compounds clomiphene [drug concentration causing 50% inhibition (IC50) = 25 microM], 4-hydroxytamoxifen (IC50 = 25 microM), and N-desmethyltamoxifen (IC50 = 8 microM). The Ca2+- and phospholipid-independent phosphorylation of protamine sulfate, which is catalyzed by protein kinase C, was not inhibited by the triphenylethylenes, suggesting that they do not interact directly with the active site of protein kinase C. The inhibitory potency of each triphenylethylene was reduced when the phospholipid concentration was increased, providing evidence that these drugs inhibited protein kinase C by interacting with phospholipids. The potencies of the effects of the triphenylethylenes on protein kinase C in the lipid environment of intact cells were evaluated by determining their efficacies in the inhibition of [3H]phorbol 12,13-dibutyrate (PDBu) binding to mouse embryo C3H/10T1/2 cells. Micromolar concentrations of each drug inhibited [3H]PDBu binding in these cells. N-Desmethyltamoxifen, 4-hydroxytamoxifen, and tamoxifen inhibited protein kinase C with the same order of potency as that which has been reported for their inhibition of MCF-7 cell growth by Reddel et al. (1983). N-Desmethyltamoxifen and 4-hydroxytamoxifen were also more potent than tamoxifen in the inhibition of the growth of mouse embryo fibroblast C3H/10T1/2 cells. These correlations suggest that the mechanism of growth inhibition by tamoxifen and its metabolites includes interactions with protein kinase C