Dynamics of the interaction between the insulin receptor and protein tyrosine‐phosphatase 1B in living cells

Abstract

The dynamics of the interaction of the insulin receptor with a substrate‐trapping mutant of protein‐tyrosine phosphatase 1B (PTP1B) were monitored in living human embryonic kidney cells using bioluminescence resonance energy transfer (BRET). Insulin dose‐dependently stimulates this interaction, which could be followed in real time for more than 30 minutes. The effect of insulin on the BRET signal could be detected at early time‐points (30 seconds), suggesting that in intact cells the tyrosine‐kinase activity of the insulin receptor is tightly controlled by PTP1B. Interestingly, the basal (insulin‐independent) interaction of the insulin receptor with PTP1B was much weaker with a soluble form of the tyrosine‐phosphatase than with the endoplasmic reticulum (ER)‐targeted form. Inhibition of insulin‐receptor processing using tunicamycin suggests that the basal interaction occurs during insulin‐receptor biosynthesis in the ER. Therefore, localization of PTP1B in this compartment might be important for the regulation of insulin receptors during their biosynthesis.