FIGURE 8.

Further stimulation of autonomous CaMKII activity toward GluR1 Ser-831 in transfected HEK cells. A, Western blot analysis of phospho-S831 and total GluR1 from extracts of transfected HEK cells before or after a Ca²⁺ signal induced by ionomycin treatment (10 μm, 3 min). HEK cells were transfected to co-express exogenous HA-tagged GluR1 and GFP-CaMKII T286D (constitutively autonomous) or T286D, T305/6D (constitutively autonomous, CaM binding impaired). B, quantification of Western blot analyses as in A showed that GluR1 Ser-831 phosphorylation by both wild type and the autonomous T286D CaMKII can be similarly and significantly increased by ionomycin-induced Ca²⁺ signals, compared with Ca²⁺/CaM-impaired mutants (T305/6D), which failed to show such increase, as expected (*, p < 0.05 in Neuman-Keuls multiple comparison test, after one-way ANOVA with p < 0.05; n = 3 or 5, for wild type or T286D, respectively). Error bars indicate S.E.