Inositol-requiring mutants of Saacharomyces cerevisiae were tested in cell extracts for the ability to convert glucose-6-phosphate to inositol-phosphate (IP synthetase) and inositol (IP phosphatase). Mutants representing any one of 10 unlinked loci conferring the inositol requirement were unable to synthesize either compound in an assay with glucose-6-phosphate as the substrate. These results indicate that the mutants lack IP synthetase activity and that at least 10 genes control the conversion of glucose-6-phosphate to inositol-phosphate. In addition, a mutation known to be unlinked with the ino1 locus interacts with a leaky ino1 allele and may play a role in the regulation of IP synthetase. This mutation causes a 47% reduction in wild-type IP synthetase activity and, when combined in a haploid strain with the leaky ino1 allele, it reduced IP synthetase activity to a level below that which is growth supporting. Wild-type and IP synthetase-deficient strains were tested for reduced nicotinamide adenine dinucleotide (NADH) accumulation, since NAD+ is required in the conversion of glucose-6-phosphate to inositol. No detectable accumulation of NADH was observed in the wild-type strain, presumably because the NADH generated is rapidly oxidized during subsequent partial reactions of IP synthetase. Mutants representing three different loci accumulate NADH and may, therefore, lack the NADH-mediated reductase activity of IP synthetase. Other mutants tested fail to accumulate NADH and may, therefore, lack the NAD+-mediated oxidase activity of IP synthetase. Phospholipid synthesis was studied by 32P pulse labeling in one mutant under conditions of inositol supplementation and starvation. Starved cells incorporate 32P into phospholipids normally for 2 h, followed by a period in which the rate of phosphatidylinositol synthesis decreases and the rate of phosphatidylcholine synthesis increases. After 5 to 6 h starvation, all cellular phospholipid synthesis ceases.
described for the first time the synthesis of mixed acidtriglycerides ().
Description of the specific presence of fatty acids in the depot fats ofruminants in contrast to their absence in non-ruminants ().
The "phospholipid effect" discovered in 1953 is now attributed to aphosphoinositide in connection with phosphatidic acid metabolism(phosphatidylinositol cycle) ().
Barber JM et al.
Phosphatidylinositol - Wikipedia
Among activators, a variety of endogenously present lipids were described ().
An antiphosphatidylcholine antibody was described in the serum of a patient diagnosed with hemolytic anemia ().
Phosphatidylserine was shown to be recognized by specific antibodies in patients with lupus anticoagulant ().
The "Nod factors" produced in legumes by as a class of signalling molecules was identified as lipo-chitooligosaccharides ().
First demonstration of phosphatidylinositol anchor on the lipopolysaccharides of a prokaryotic species, ( ).
Demonstration of the induction of the synthesis of proteinase inhibitors by methyl jasmonate in a wounded plant but also in nearby plants through the atmosphere ().
First clear demonstration that fatty acids are as unfavorable as saturated fatty acids in raising LDL cholesterol and lowering HDL cholesterol levels ().