Figure 6.

FER-KD autophosphorylation is essential for initiating substrate phosphorylation.

(A) Time-course analysis of FER-KD trans-phosphorylation of the GRP7 substrate. Samples were incubated with 1 mM ATP and 10 mM Mg²⁺ at 25°C for the indicated period.

(B) Time-course analysis of FER-KD trans-phosphorylation of the MYC2 substrate. Samples were incubated with 1 mM ATP and 10 mM Mg²⁺ at 25°C for the indicated period.

(C)Trans-phosphorylation of the GRP7 substrate by FER variants with a single mutation in the activation segment. Samples were incubated with 1 mM ATP and 10 mM Mg²⁺ at 25°C for 60 min.

(D)Trans-phosphorylation of the MYC2 substrate by FER variants with a single mutation in the activation segment. Samples were incubated with 1 mM ATP and 10 mM Mg²⁺ at 25°C for 60 min.