Two Forms of GO Type G Proteins: Identification and Distribution in Various Rat Tissues and Cloned Cells

A G(o) type G protein distinct from the major species of G(o) was recently isolated from bovine brain and designated G(o)*. The cDNAs encoding two forms of mammalian G(o) alpha were also isolated and designated GoA alpha and GoB alpha. To recognize two forms of G(o) type G proteins, we raised antibodies in rabbits against two peptides with sequences found only in the respective proteins of murine GoA alpha (SNTYEDAAAYIQTQF) and GoB alpha (TEAVAHIQGQYWSK). Purified anti-GoA alpha antibodies reacted with the major species of G(o) alpha purified from bovine and rat brain, whereas anti-GoB alpha antibodies reacted only with rat G(o)*alpha, but not with the major species of G(o) alpha or bovine G(o)*alpha. These results indicate that the major species of G(o) alpha is encoded by GoA alpha cDNA and G(o)*alpha is encoded by GoB alpha cDNA. Using these antibodies, the distribution of GoA and GoB was studied in various rat tissues and cloned cells. Both GoA and GoB were present in many tissues, but their distribution in peripheral tissues was distinct. GoA alpha seemed to associate mainly with neural tissues. On the other hand, relatively high concentrations of GoB alpha were present in the brain, pituitary gland, adipose tissue, lung, and testis. The concentrations of both GoA and GoB in the brain increased during ontogenic development, but the increase in GoB was observed at a later age. Both GoA and GoB were found in such cloned cells as PC12, NG108-15, C6, GA-1, G8, and 3T3-L1 cells. Treatment of PC12 cells with nerve growth factor caused the extension of neuron-like processes and the increase in the level of GoA, but not in the level of GoB.     

Copurification of small heat shock protein with alpha B crystallin from human skeletal muscle.

Immunoreactive alpha B crystallin and a 28-kDa protein in an extract of human pectoral muscle were precipitated by (NH4)2SO4 at 40% saturation, and coeluted during column chromatography on DEAE-Sepharose and on Bio-Gel A-5m. The two proteins were separated on a column of S-Sepharose HP in the presence of 7 M urea. Further chromatography of each of the two resultant fractions on a column of Superdex 75 pg and on a TSK-SP 5PW column in the presence of urea yielded preparations of alpha B crystallin and the 28-kDa protein each of which gave a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The final preparation of 28-kDa protein contained at least two subtypes, which were separable on the TSK-SP column. However, fragmentation patterns of the two major 28-kDa proteins after digestion with endoproteinase Asp-N were identical. Amino acid sequences of peptides formed by cleavage of the purified 28-kDa protein and alpha B crystallin were identical to those of particular regions of the deduced amino acid sequences of human small heat shock protein (HSP28) and lens alpha B crystallin, respectively. Using an immunoassay method, with antibodies raised in rabbits, we found that HSP28 was present in all human tissues tested and at high levels (greater than 1 micrograms/mg protein) in the heart and other tissues composed of striated and smooth muscles. HSP28, found with alpha B crystallin, in extracts of several human and bovine tissues was trapped on and coeluted with alpha B crystallin from an affinity column prepared with antibodies against alpha B crystallin. This result suggests that the two proteins are associated in cells.     

Synthesis of 2,2,2-trichloroethyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-d-glucopyranoside,and its reaction with glycosyl halides.

2,2,2-trichloroethyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-d-glucopyranoside (9) was synthesized in 6 steps from the readily available 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranose in 25% overall yield by employing the stannyl method for the regioselective activation of hydroxyl groups. Dibenzyl ether 9 was then glycosylated with appropriate glycosyl donors to afford lactosamine and chitobiose derivatives in good yield.     

Synthesis of 3,6-di-O-acetyl-2-deoxy-2-phthalimido-4-O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-β-d-glucopyranosyl chloride

A lactosaminyl donor, 3,6-di-O-acetyl-2-deoxy-2-phthalimido-4-O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-β-d- glucopyranosyl chloride, was synthesized in 10 steps, starting from 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranose. Benzyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-d-glucopyranoside was prepared by regioselective benzylation at the primary hydroxyl group by the stannyl method, and was used as a key intermediate.

     

Disappearance of calcium-induced phase separation in phosphatidylserine-phosphatidylcholine membranes caused by protonation and by electric current

Disappearance of Ca²⁺-induced phase separation in phosphatidylserine-phosphatidylcholine membranes has been studied under several conditions by monitoring electron spin resonance spectrum of spin-labeled phosphatidylcholine. The membranes were prepared in Millipore filters. Electron micrographs of the preparations showed formation of multilayered structures lined on the pore surface. The phase separation was disappeared when the membrane was soaked in non-buffered salt solution (100 ml KCl, pH 5.5). It was markedly contrasting that when the bathing salt solution was buffered no disappearance was observed. Disappearance of the phase separation was also observed when the Ca²⁺-treated membrane was transferred to acidic salt solutions ($\text{?}\text{pH 2.5}$) or to low ionic strength media ($\text{? 10}\text{mM}$) buffered at pH 5.5, and then to the buffered salt solution (100 mM KCl, pH 5.5). These are due to replacement of Ca²⁺ by proton, proton-induced separation, followed by disappearance of the phase separation inthe buffered salt solution. Biological significance of the competition between Ca²⁺ and proton for the phase separation or domain formation in the membranes was emphasized.     

Acyl migrations in diacyl derivatives of 2-methylmercaptobenzimidazole : A model of biotin

Diacyl derivatives of 2-methylmercaptobenzimidazole undergo the tautomerization 2 1 2′. Thermodynamic predominancy of one isomer over the others depends on the substituents on carbonyl groups. It has been found that electron-withdrawing substituents tend to favor 2-type compounds, whereas electron-releasing substituents make 1-type compounds more stable. The migration has been extended to include the carboethoxy group, and the results are discussed in relation to the mechanism of biotin-dependent enzymic carboxylation.     

Concanavalin A-peroxidase-diaminobenzidine (Con A-PO-DAB)-alcian blue (AB)

Summary A method has been established for the dual staining of complex carbohydrates in light microscopy. It is a combined concanavalin A-peroxidase-diaminobenzidine (Con A-PO-DAB)-alcian blue (AB) (pH 2.5) method, and with this method it is possible to color -D-glucosyl and -D-mannosyl residues and acidic groupings of complex carbohydrates in tissues brown and blue respectively. Histochemical experiments using histological sections with reactive complex carbohydrates and casein films containing carbohydrates of known chemical structure have substantiated the validity of the above significance of the dual staining. Thus, the present dual staining method is a reliable one and a new addition to a series of dual staining techniques hitherto employed in the light microscopic histochemistry of complex carbohydrates.This investigation was supported in part by a Grant-in-Aid from the Japanese Education Ministry (1975)     

Metabolism of PG in man: Effect of furosemide on the excretion of the main metabolite of PG F2α

The excretion rates of main urinary metabolite of PG F₂α were measured radioimmunologically in 4 healthy persons and in 13 essential hypertensives. The resting values were 9.3±0.73 in the former and 10.4±2.17 ng/min in the latter. There was no significant differences between them. The excretion of the metabolite decresed prominently after the administration of furosemide. The percent decrease was 57% in healthy persons and 70% in essential hypertension. The percent result supports that furosemide inhibit the catabolism of PG F₂α.     

Effect of phenformin on the response of plasma intestinal glucagon-like immunoreactivity (GLI) to oral glucose in gastrectomized subjects.

The effect of phenformin (DBI) on the plasma intestinal glucagon-like immunoreactivity (GLI) and pancreatic glucagon (IRG) responses to oral and intravenous glucose loads were studied in 26 gastrectomized subjects, using a cross-reacting and an IRG-specific anti-serum. The drug produced no significant changes in fasting GLI and IRG levels. Thirty minutes after oral glucose alone, the total GLI level rose to a peak of 1.55 +/- 0.17 ng/ml in the untreated subjects and to a maximum level of 1.67 +/- 0.18 ng/ml in the DBI-pretreated subjects. However, the mean GLI levels obtained 120 and 180 min after oral glucose were significantly higher after treatment with DBI. The blood sugar and IRI responses to oral glucose were lowered significantly by DBI pretreatment. DBI did not alter the glucose, IRI, IRG and GLI response to intravenous glucose. These results suggest that the release of intestinal GLI is not related to the intestinal absorption of glucose.