Compartmentalization of transport and phosphorylation of glucose in a hepatoma cell line

Richard R. Whitesell*, Hossein Ardehali, Joseph M. Beechem, Alvin C. Powers, Wieb Van Der Meer, Laureta M. Perriott, Daryl K. Granner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The first steps of glucose metabolism are carried out by members of the families of GLUTs (glucose transporters) and HKs (hexokinases). Previous experiments using the inhibitor of glucose transport, CB (cytochalasin B), revealed that compartmentalization of GLUTs and HKs is a major factor in the control of glucose uptake in L6 myotubes [Whitesell, Ardehali, Printz, Beechem, Knobel, Piston, Granner, Van Der Meer, Perriott and May (2003) Biochem. J. 370, 47-56]. In the present paper, we evaluate compartmentalization of GLUTs and HKs in a hepatoma cell line, H4IIE, which is characterized by excess GLUT activity, HKI in a paniculate and a cytosolic fraction, and insignificant G6Pase (glucose-6-phosphatase) activity. The measured activity of glucose transport exceeded the rate of phosphorylation approx. 30-fold. Treatment with 25 μM CB (Ki ≃ 3 μM in H4IIE cells) paradoxically increased the excess of GLUTs over phosphorylation (GLUTs are inhibited 80%, while phosphorylation is inhibited 98%). The global relationships of the data could be reconciled most simply by a two-compartment model. In this model, phosphorylation of glucose is carried out by a subset of HK molecules supplied by a subset of GLUTs that are more sensitive to CB than the other GLUTs. The agent, DCC (dicyclohexylcarbodi-imide) caused HKI to translocate from the paniculate compartment to the cytosolic compartment and potently inhibited glucose phosphorylation. The particulate compartment may represent the mitochondria, to which the more CB-sensitive GLUTs may control the transport of glucose.

Original languageEnglish (US)
Pages (from-to)245-253
Number of pages9
JournalBiochemical Journal
Volume386
Issue number2
DOIs
StatePublished - Mar 1 2005

Keywords

  • Dicyclohexylcarbodi-imide
  • Flux control
  • Global analysis
  • Hexokinase
  • Hexose transport
  • Sensitivity analysis

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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