CKLiK activity requires Ca⁺⁺/Calmodulin and regulates the transcription factors CREM and CREB.

(A) COS cells were transfected with 10 μg HA_CKLiK. Recombinant CaMKI was used as a positive control. Cells were stimulated with or without 1 μmol/L ionomycin as indicated. HA_CKLiK was immunoprecipitated from whole cell lysates and kinase assays were performed in the presence or absence of Ca⁺⁺/calmodulin as indicated. CREMβ-WT (33 kd) and mutated CREMτ-S117A (42 kd) were used as substrate. Data represent 1 of 4 independent experiments. (B) Cells transfected with GAL4-CAT reporter construct (2 μg) and fusion construct of CREB_GAL4 or CREB-S133A_GAL4 (2 μg) (indicated as CREB-WT and CREB-S133A, respectively), were cotransfected with CKLiK (4 μg) or with control vector as indicated. Stimulation with or without 1 μmol/L ionomycin and CAT reporter assays were performed as described in “Materials and methods.” Data are indicated as counts per minute (cpm) and represent at least 3 independent experiments ± SEM.