Figure 2.

Structural alignment, intron positions and phylogeny. The gray boxes in the middle of the picture show the actual amino acid sequence alignment of the proteins included in the analysis whereas the black boxes at the top indicate the position of the structurally conserved elements, transmembrane helices (H1-H6) and the NPA-boxes. The central portion of the alignment used in phylogenetic analyses is delimited by the vertical dotted lines, excluding the N- and C-terminal regions. The coloured arrows indicate intron positions in the corresponding coding sequence, where the colours represent the relative position within the codon. The tree to the left is the Maximum Likelihood tree where the length of the branches is representative of sequence divergence. To the right a consensus tree based on the results from the maximum likelihood analysis is depicted, showing the stability of the clustering of sequences. The bootstrap support in percent is indicated at each node (nodes with bootstrap support lower than 50% are collapsed) and for nodes with a Bayesian posterior probability above 90% this number is also circled. Horizontal dotted lines separate clearly distinguishable clusters. The coloured branches in the consensus tree highlight from which phyla the plant MIPs were derived, see also Figures 1 and 7.