Figure 3.

Tryptic phosphopeptide maps of Wee1 K242I. Wee1 K242I was labeled by incubation with [γ-³²P]ATP and activated p42 MAPK in vitro (A and D) or by incubation with [γ-³²P]ATP in control interphase extracts (B) or in interphase extracts preincubated for 30 min with Mos (1 μM; C and D). Tryptic digests were performed, and equal numbers of counts were subjected to thin-layer electrophoresis (TLE; pH 8.9, anode to the left) followed by TLC in phosphochromatography buffer. (A) Wee1 K242I phosphorylated by p42 MAPK in vitro. (B) Wee1 K242I phosphorylated in interphase extracts, with no added Mos. (C) Wee1 K242I phosphorylated in Mos-treated interphase extracts. (D) Mix of the samples used in A and C.