MALDI-Tof MS analyses of CLV3 peptides with N-terminal extensions. Spectra of CLV3p12 (A), L-CLV3p13 (B), EEL-CLV3p15 (C), HEEL-CLV3p16 (D), LHEEL-CLV3p17 (E), and LHEEA-CLV3p17 (F) after 3-d incubations with Ler seedlings. Sequences of the original peptides are shown on the upper right of each figure, and the observed cleavage sites are marked by black arrowheads; sequences of fragments are labeled next to corresponding peaks. Original peptides, blue arrowheads; CLV3p12, red arrowheads. The Ala substitution in F is in red.