TABLE 1

Glucokinase activity and glucose responsiveness of MIN6, INS 1E, and βTC-tet cells

MIN6INS 1EβTC-tet
Glucokinase activity (mU/mg protein)
    Supernatant2.5 ± 0.31.8 ± 0.30.1 ± 0.04
    Pellet0.7 ± 0.2NDND
Glucose phosphorylation (nmol · 3 h−1 · mg−1)
    5 mmol/l glucose104 ± 12143 ± 12137 ± 20
    25 mmol/l glucose268 ± 26*354 ± 14*275 ± 30*
Insulin secretion (μg · 2 h−1 · mg protein−1)
    5 mmol/l glucose435 ± 52267 ± 46NM
    25 mmol/l glucose1,370 ± 167*1,005 ± 105*NM
  • Data are means ±SE, n = 4–16. Glucokinase was determined spectrometrically in supernatant and pellet fractions of cell homogenates. Glucose phosphorylation and insulin secretion were determined at 5 and 25 mmol/l glucose.

  • *

    * P < 0.001 relative to 5 mmol/l glucose. ND, not detectable; NM, not measured.