Figure 1.

Structure of mouse F3/Contactin and relationships to further Ig superfamily components. (A) F3/Contactin molecule is built by the association of Immunoglobulin type C2 domains, located in its N-terminal half (Ig Type C2), with Fibronectin type III domains (FN Type III), which map to the premembrane region. Attachment to the neuronal membrane is mediated by a glycosylphosphatidylinositol-containing lipid tail (GPI). (B) Phylogram comparing different GPI-anchored components of the IgC2/FNIII family.¹⁴⁹ Note that all mammalian members of the F3/Contactin family are close to each other, lower score being oberved with chick and fish and, mostly, with Drosophila orthologs. As for the other components of the same family, highest scores were found with both mouse and human TAG-1, while Big-1 and Big-2, NB2 and NB3 were more evolutionary distant.