FIGURE 9.

CaMKII requires a domain C-terminal of its binding site to regulate NHE3 activity. PS120/NHERF2 cells stably transfected with NHE3 truncated to aa 690 (NHE3/Δ690V) were exposed to 30 μm KN-62 as in Fig. 1, and the effect on NHE3 activity was determined. KN-62 failed to affect NHE3 activity of the truncation mutant suggesting that the C-terminal 143 aa of NHE3 are required for the CaMKII inhibition of NHE3 activity. Note that basal NHE3 activity in NHE3/Δ690V cells is much faster than full-length NHE3, as reported (33). N refers to the number of separate experiments. NS, not significant.