Regulation and intracellular localization of the biotin holocarboxylase synthetase of 3T3-L1 cells

Hyo I. Chang, Nadine D. Cohen

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27 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)237-247
Number of pages11
JournalArchives of Biochemistry and Biophysics
Issue number1
Publication statusPublished - 1983 Aug

Bibliographical note

Funding Information:
i These studies were supported in part by research grants from the National Institutes of Health (AM 38651) and National Science Foundation (PCM 8103270). ‘To whom requests for reprints should be addressed.

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology


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