Model for coassembled SK2, CaM, CK2, and PP2A. The model, consistent with pull-down results, represents two of the four SK2 subunits and invokes an intersubunit interaction. CK2 and PP2A are drawn approximately to scale. In this configuration, the N-terminal domain of SK2 that includes K121 is positioned close to CK2 that binds to the adjacent sequence, RRALF.