Figure 3.

Phylogenetic tree of the neurexin protein family. Dendrogram showing the phylogenetic relationships between the vertebrate and invertebrate neurexins. The tree was generated using neurexin amino acid sequences from several vertebrate species and invertebrate homologs, and a gap-free sequence alignment with GeneBee [132]. The neurexin 1 (Nrxn1) family is shown in red, neurexin 2 (Nrxn2) in blue, and neurexin 3 (Nrxn3) in green. The invertebrate sequences are shown in black. Species names and GenBank accession numbers [133] are given for each branch. Cluster distance values indicated at branches represent the amino acid differences for the particular group of sequences. Note that the more distantly related Caspr/paranodin/CTNAP family member ‘neurexin 4’ contains a different domain structure and is not included in the analysis.