Differential influence of cAMP on the expression of the three subtypes (ATA1, ATA2, and ATA3) of the amino acid transport system A

Takahiro Hatanaka, Wei Huang, Robert G. Martindale, Vadivel Ganapathy

Research output: Contribution to journalArticle

29 Scopus citations


Treatment of HepG2 cells with forskolin led to 60-100% stimulation of system A activity, measured as the Na+-dependent uptake of α-(methylamino)isobutyric acid. The stimulation was reproducible with cholera toxin and dibutyryl cAMP, and inhibitable by H7, a non-specific protein kinase inhibitor. The stimulatory effect was eliminated by cycloheximide and actinomycin D. The forskolin effect was associated with an increase in the maximal velocity of the transport system, with no change in substrate affinity. These cells express three different subtypes of system A (ATA1, ATA2, and ATA3). Treatment with forskolin increased the steady-state levels of ATA1 and ATA2 mRNAs, but decreased that of ATA3 mRNA.

Original languageEnglish (US)
Pages (from-to)317-320
Number of pages4
JournalFEBS Letters
Issue number2
StatePublished - Sep 14 2001



  • Amino acid transport
  • Cyclic AMP
  • Human liver cell line
  • Subtypes of system a
  • Transport regulation

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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