Figure 4.

Close-up of Type II CBL clade from ML tree shown in Figure 2. Confidence scores (aLRT) are shown for each clade, and the yellow star denotes an inferred intron loss event. Some clades are unlabeled or collapsed for clarity (see full tree in Supplementary File S2). Type II CBLs are distinguished by the presence of an N-terminal tonoplast targeting sequence (TTS), however certain members (asterisks) of the Type II clade have lost or degenerate TTSs. Arabidopsis CBLs in this clade (green dots) contain the TTS or a degenerate form of it; whereas the two Physcomitrella CBLs (yellow dots) in this clade sharply differ in that CBL2 has a Type I dual-lipid modification motif and CBL3 has a TTS. Presence of the TTS in Selaginella homologs within the clade (see Figure 3) suggests that CBL2 has lost its TTS, through a mechanism such as gene conversion, for example.