Gem is a member of the RGK (Rad/Gem/Kir) family that regulates calcium channel handling. Gem over-expression inhibits insulin release in insulin-secreting Min6 cells.
Gem-deficient mice were generated. They were glucose intolerant and had impaired glucose stimulated insulin secretion. On isolation, islets of Gem-deficient mice have decreased free calcium responses to glucose and smaller amplitude and frequency of calcium oscillations upon glucose stimulation. Unexpectedly, insulin secretion in Gem islets improved in response to calcium channel inhibitors.