Regulation and intracellular localization of the biotin holocarboxylase synthetase of 3T3-L1 cells.
A quantitative assay has been developed to measure holocarboxylase synthetase activity in cellular extracts. This assay was based on measuring the incorporation of [3H]biotin of high specific activity (4.3 Ci/mmol) into purified rat liver apopyruvate carboxylase. With this assay, holocarboxylase synthetase in 3T3-L1 mouse fibroblasts has been monitored. During the differentiation of this cell from a fibroblast to an adipocyte, holocarboxylase synthetase activity was found to increase threefold, while pyruvate carboxylase activity rose 20-fold. The results suggest a possible relationship between the activity of the holocarboxylase synthetase and the level of the biotin-dependent carboxylases within the mammalian cell. Utilizing digitonin fractionation. the intracellular distribution of this enzyme has also been examined. In the 3T3-L1 cell, the large majority (approximately 70%) of the total holocarboxylase synthetase activity was found in the cytosolic compartment.
D000818:Animals; D001665:Binding Sites; D019731:Carbon-Nitrogen Ligases; D002454:Cell Differentiation; D003600:Cytosol / Q000201:enzymology; D005347:Fibroblasts / Q000201:enzymology; D007700:Kinetics; D007739:L Cells / Q000201:enzymology; D008025:Ligases / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D008297:Male; D051379:Mice; D051381:Rats; D011919:Rats, Inbred Strains
D008025:Ligases; D019731:Carbon-Nitrogen Ligases; C023312:holocarboxylase synthetases