The effect of ts-mutation on expression of genes induced by heat shock in Drosophila melanogaster. III. Synthesis of proteins cognate to HSP70

2D-electrophoresis performed as described by O'-Farrel has revealed clear-cut differences in the pattern of proteins synthesized in the cells of wild-type flies and in the cells of ts-lethal. The cells of the mutant studied after heat-shock exhibit not only the lack of HSP83 and HSP35 but also the absence of a few of the heat-shock proteins belonging to the HSP70 group. Moreover, in the cells of the mutant an intensive synthesis of a protein with mol. weight 72 KDa was observed after heat-shock. This protein belongs to highly abundant heat-shock cognate proteins (HSCP) which are usually not induced by temperature elevation.     

Isolation of apolipoproteins A-I, A-II and E and their estimation by rocket immunoelectrophoresis in blood plasma of dis-alpha-lipoproteinemic patients

The methods for isolation of pure apolipoproteins A-I, A-II and E from the blood plasma of donors for preparation of monospecific rabbit antisera against these apolipoproteins and their estimation in human blood plasma using immunoelectrophoresis are described. It was found that the average content of apolipoprotein A-I (apo A-I) in the blood plasma of healthy males is 126.6 mg%, that of apolipoprotein A-II (apo A-II) is 56.8 mg%, that of apolipoprotein E (apo E) is 10.2 mg%. The apo A-I content in blood plasma is increased in hyper-alpha-lipoproteinemic patients and is decreased in hypo-alpha-lipoproteinemic ones, i. e. there is a direct relationship between the changes in concentration of high density lipoproteins (HDL) and apo A-I. The concentration of apo A-II in dis-alpha-lipoproteinemias varies within a narrow range. A considerable increase of the alpha-cholesterol/apo A-I ratio suggesting an increased capacity of HDL to transport cholesterol in hyper-alpha-lipoproteinemic patients is observed. There exists an indirect correlation between the changes in the contents of apo A-I and apo E in dis-alpha-lipoproteinemic patients.     

Decarboxylation of malonyl-CoA and biosynthesis of mevalonic acid in rat liver]

Biosynthesis of mevalonic acid (MVA), total formation of 14CO2 from [1,3-14C]malonyl-CoA and the activity of malonyl-CoA decarboxylase in subcellular fractions of rat liver were studied. The dependence of the rate of MVA biosynthesis on malonyl-CoA concentration was found to be linear both in 140,000 g supernatant and solubilized microsomal fractions. It was shown that in a composite system (140,000 g supernatant fraction added to washed microsomes, 10 : 1) the optimal concentration ratio for the substrates of MVA biosynthesis (malonyl-CoA and acetyl-CoA) is 1 to 2. In the absence of acetyl-CoA decarboxylation of [1,3-14C]malonyl-CoA was prevalent. In all subcellular fractions studied decarboxylation of [1,3-14C]malonyl-CoA prevailed over its incorporation into MVA, total non-saponified lipid fraction and fatty acids. The degree of malonyl-CoA, decarboxylation was not correlated with the rate of its incorporation into MVA, i. e. the increase in the 14CO2 formation was not accompanied by stimulation of [1,3-14C]malonyl-CoA incorporation either into MVA or into total non-saponified lipid fractions. The incorporation of [1-14C]acetyl-CoA into MVA under the same conditions was considerably lower than that of [1,3-14C]malonyl-CoA. In all subcellular fractions under study the activity of malonyl-CoA decarboxylase was found. The experimental data suggest that a remarkable part of malonyl-CoA is incorporated into MVA without preliminary decarboxylation. A possible role of malonyl-CoA decarboxylase as an enzyme which protects the cell against accumulation of malonyl-CoA and its immediate metabolites -- malonate and methylmalonyl-CoA is disucssed.     

Heme-heme interactions in circular dichroism spectra

Using the theory of optical activity by Kirkwood and Tinoco, the CD spectra of the heme peptides in mono- and dimeric forms have been calculated according to the simple spectral model of heme of Simpson.     

Yeast hnRNP K-Like Genes Are Involved in Regulation of the Telomeric Position Effect and Telomere Length

Mammalian heterogeneous nuclear ribonucleoprotein K (hnRNP K) is an RNA- and DNA-binding protein implicated in the regulation of gene expression processes. To better understand its function, we studied two Saccharomyces cerevisiae homologues of the human hnRNP K, PBP2 and HEK2 (heterogeneous nuclear RNP K-like gene). pbp2Delta and hek2Delta mutations inhibited expression of a marker gene that was inserted near telomere but not at internal chromosomal locations. The telomere proximal to the ectopic marker gene became longer, while most of the other telomeres were not altered in the double mutant cells. We provide evidence that telomere elongation might be the primary event that causes enhanced silencing of an adjacent reporter gene. The telomere lengthening could, in part, be explained by the inhibitory effect of hek2Delta mutation on the telomeric rapid deletion pathway. Hek2p was detected in a complex with chromosome regions proximal to the affected telomere, suggesting a direct involvement of this protein in telomere maintenance. These results identify a role for hnRNP K-like genes in the structural and functional organization of telomeric chromatin in yeast.