Fig. 1.

Schematic outline of a phylogenetic tree of the SM protein Munc18 demonstrates that the core machinery of the secretory apparatus of M. brevicollis is closely related to animals. Detailed versions of the Munc18 tree and also of the SNAP-25 and syntaxin1 trees are shown in Fig. S1. The major eukaryotic lineages are emphasized by different colors, expansions in the vertebrate lineage are indicated. In addition, the position of Munc18 from M. brevicollis (Munc18) is shown. Whereas M. brevicollis possesses only one Munc18 homolog expansion of Munc18-like factors occurred in vertebrates, giving rise to the three isoforms Munc18-1, -2, and -3. The labels on the major branches represent the Likelihood Mapping (Left) and almost unbiased (AU) support values (Right).