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Fig. 1. Proposed mechanism for the activation of insulin receptor activity by LMWCr in response to insulin. The inactive form of insulin receptor (IR) is converted to the active form by binding insulin (I). This triggers a movement of chromium from the blood into insulin-dependent cells, which in turn results in apoLMWCr (triangle) binding chromium. Finally, the holoLMWCr (square) binds to insulin receptor, further activating the receptor kinase activity. ApoLMWCr is unable to bind to receptor and activate kinase activity. When the insulin concentration drops, holoLMWCr may be released from the cell to relieve its effects. Thus, LMWCr functions on the inside of the cell and does not affect insulin. Adapted, with permission, from Davis CM, Vincent JB: Chromium in carbohydrate and lipid metabolism. J Biol Inorg Chem 2:675–679, 1997.
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