Fig. 2

Localizations of insulin and Rab27A in the MIN6 mouse pancreatic β cell line. (A) Effect of the glucose concentration on localizations of insulin and V5-Rab27A. Cells expressing V5-Rab27A were sequentially incubated with 2.2 mM glucose for 60 min, 20 mM glucose for 5 min, and 2.2 mM glucose for 5 min, and then stained with antibodies specific for insulin (magenta) and V5 (green). Merged images are also shown. (B) Peripheral localization of insulin. The cell peripheral area was defined as the region between the cell edge (yellow solid line) and 0.75 µm inside from this edge (yellow dotted line). Cells with peripheral insulin or V5-Rab27A were defined as those in which the average signal intensity of insulin or V5-Rab27A in the cell peripheral area was more than twice that in the other area. (C) Cells with peripheral insulin and V5-Rab27A according to the glucose concentration. The percentages of cells with peripheral insulin (magenta) and V5-Rab27A (green) as defined in (B) were calculated at each glucose concentration. Data are means ± S.E. from four independent experiments. n > 30 cells in each experiment. (D) Localization of Rab27A to insulin granules. Co-localization was quantified as the percentage of insulin-positive pixels that were also Rab27A-positive. More than 30 cells were randomly selected from four experiments. Data are means ± S.E.