FIG. 3.
(A) Potential sites of phosphorylation by ERK in TEL. Potential phosphorylation sites that meet a minimal consensus sequence (Ser/Thr-Pro) and reside within the region comprising amino acids 206 to 267 are boxed. Numerals are amino acid numbers in the TEL protein. (B) Structures of alanine mutants. The potential serine residues for phosphorylation, Ser22, Ser213, Ser238, and Ser257, were replaced with alanines. Asterisks show the positions of the residual serine residues. (C) ERK-dependent size shifts of wild-type TEL and its alanine mutants. COS-7 cells were transfected with 5 μg of pME18S-FLAG-TEL (lanes 1 and 2), pME18S-FLAG-S22 (lanes 3 and 4), pME18S-FLAG-S213 (lanes 5 and 6), pME18S-FLAG-S238 (lanes 7 and 8), pME18S-FLAG-S257 (lanes 9 and 10), or pME18S-FLAG-S-null (lanes 11 and 12) alone (lanes 1, 3, 5, 7, 9, and 11) or in combination with 5 μg of ERK expression plasmid (lanes 2, 4, 6, 8, 10, and 12) and treated as described in the legend to Fig. 2B. Western analysis was performed with anti-FLAG antibody. Positions of size markers (in kilodaltons) are shown.