FIGURE 3.
CaMKIIα is targeted to F-actin by the α-actinin-2 CTD in cells. A, CaMKII immune complexes isolated from extracts of HEK293 cells co-expressing TT305/6AA-CaMKIIα with full-length HA-actinin-2 (HA-A2; WT or mutated) were analyzed by protein stain for CaMKII and immunoblotting for HA. B, immunofluorescence microscopy of HEK293 cells expressing TT305/6AA-CaMKIIα (AA-CaMKII, red) alone (top) or with HA-actinin-2 (WT or Y861R; green). C, localization of AA-CaMKII and F-actin (phalloidin staining; blue) in the absence and presence of WT HA-actinin-2 (green). Arrows indicate colocalization of HA-A2 and AA-CaMKII alone (yellow) or HA-A2, AA-CaMKII and phalloidin (white). D, intensity correlation quotient (ICQ) analysis of colocalization between AA-CaMKII and WT or Y861R HA-actinin-2 (left) or AA-CaMKII and phalloidin in the presence and absence of WT HA-actinin-2 (right) (n = 8 cells; ***, p < 0.0001 versus WT by t test; **, p < 0.005 versus control by t test, n = 6 cells)