PubMed · 93754
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J Geller, J Albert. 1979. Some current problems relating to androgen receptor methodology.. https://pubmed.ncbi.nlm.nih.gov/93754/
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This paper presents data about the presence of the NMN adenylyltransferase at the nuclear matrix level of human placenta nuclei. It was found that 40-45% of the activity (depending on the extraction procedure) referred to the total nuclear NMN adenylyltransferase was tightly associated with this subnuclear compartment. The matrices purified by two different procedures exhibited DNA, RNA and protein contents comparable with those described in literature. Extensive digestion of human placenta nuclei with DNase I was not able to solubilize the NMN adenylyltransferase activity. Therefore, the data we present are consistent with the conclusion that a part of the total nuclear NMN adenylyltransferase is associated with the nuclear matrix.
We studied the oxidation of [1-14C]phytanic acid, 3-methyl substituted fatty acid, to pristanic acid and 14CO2 in human skin fibroblasts. The specific activity for alpha-oxidation of phytanic acid in peroxisomes was 29- and 124-fold higher than mitochondria and endoplasmic reticulum. This finding demonstrates for the first time the presence of fatty acid alpha-oxidation enzyme system in peroxisomes.
Because the envelope phosphatidate phosphatase plays a pivotal role in chloroplast glycerolipid metabolism, we have analyzed whether diacylglycerol could be a regulatory factor of the enzyme. Using isolated envelope membranes in which the level of diacylglycerol was modified by thermolysin treatment of intact chloroplasts to destroy the galactolipid:galactolipid galactosyltransferase, we have demonstrated that phosphatidate phosphatase activity was reduced when the membrane was enriched in diacylglycerol. All 1,2-diacylglycerol molecular species assayed were demonstrated to inhibit the enzyme to about the same extent. Kinetic studies with envelope from thermolysin-treated chloroplasts were performed in the absence and presence of diacylglycerol, and diacylglycerol was shown to be a powerful competitive inhibitor of the reaction. Finally, using isolated intact spinach chloroplasts, we have demonstrated that in situ phosphatidate phosphatase activity can be modulated by the level of diacylglycerol present in the membrane. The relevance of phosphatidate phosphatase inhibition by diacylglycerol in the regulation of chloroplast glycerolipid biosynthesis is discussed.