Control of Glucose Phosphorylation and Glucose Usage in Clonal Insulinoma Cells

Glucose metabolism was investigated in two established clonal insulinoma cell lines (RINm5F and HIT) and in a newly developed line of mouse insulinoma cells (IgSV195). The hexokinase capacity in the homogenates of RINm5F cells was 22.1 ± 3.23 U/g protein, but glucokinase was barely detectable (0.06 ± 0.013 U/g protein). In contrast, both HIT and IgSV195 cells contained glucokinase (1.5 ± 0.17 and 1.0 ± 0.16 U/g protein, respectively) in addition to hexokinase activity. Glucose usage by the intact cells qualitatively reflected the glucose phosphorylation found in the cell-free extracts. RINm5F cells exhibited a high glucose usage rate with one high-affinity component, whereas both HIT and IgSV195 cells showed two components with different glucose affinities. HIT and IgSV195 cells may be useful for a model of pancreatic β-cell glycolysis.