CK1δ Kinase Activity Is Modulated by Chk1-Mediated Phosphorylation
Figure 4
CK1δ shows species-specific differences in its sequences and phosphorylation by Chk1.
(A) Alignment of the rat CK1δ sequence with the human CK1δ transcription variants (TV) 1 and 2. (B) GST-CK1δ375–428 rat (FP1183), GST-CK1δ375–415 TV1 (human, FP1341), and GST-CK1δ375–409 TV2 (human, FP1343) were phosphorylated by Chk1 in vitro. The phosphorylated proteins were separated by SDS-PAGE and Chk1-mediated phosphorylation was quantified by Cherenkov counting of phosphorylated substrate bands. Results are shown as normalized bar graph. (C) GST-CK1δ375–428 rat (FP1183), GST-CK1δ375–415 TV1 (FP1341), and GST-CK1δ375–409 TV2 (FP1343) were phosphorylated by Chk1 in vitro and processed for two-dimensional phosphopeptide analyses as described in the Materials and Methods section.