Calcineurin signaling in MIN6 β cells

(A) A FRET-based calcineurin activity reporter (CaNAR), which consists of a calcineurin substrate sandwiched between CFP and YFP. (B) Dual imaging of Ca2+ (red) and calcineurin activity (black) revealed integrative cytosolic calcineurin activity, contrasted by an oscillatory activity pattern on the ER, in response to Ca2+ oscillations. (C) These data are consistent with a model in which free Ca2+/CaM is less abundant near the ER surface, thereby leading to weaker calcineurin activation and calcineurin activity oscillations in this compartment.