Figure 5. Ng localization at the plasma membrane is mediated by the IQ motif.

Upper panels: NIH-3T3 cells were transfected with several wild-type Ng (Ng-WT) and Ng mutants as indicated. Cells transfected with Ng and Ng-I33Q displayed a typical distribution with strongly labelled craters, whereas Ng-IQless labelling was limited to intracellular puncta. Double-Ng distribution was characterized by its abundant presence at the plasma membrane. Scale bars, 25 μm. Lower panel: binding between CaM–agarose and several Ng mutants was assayed as described in the text. The results are expressed as the ratio between bound (P) and unbound (S) Ng in each assay. Note that Ng, Ng-S36A and Ng-C3,4,9S showed a similar binding to CaM, and Ng-IQless and Ng-I33Q did not bind CaM. Ng-S36D showed an intermediate level of CaM binding. Results are means±S.E.M. for four independent experiments.