Neurotactin functions in concert with other identified CAMs in growth cone guidance in Drosophila.

We have isolated and characterized mutations in Drosophila neurotactin, a gene that encodes a cell adhesion protein widely expressed during neural development. Analysis of both loss and gain of gene function conditions during embryonic and postembryonic development revealed specific requirements for neurotactin during axon outgrowth, fasciculation, and guidance. Furthermore, embryos of some double mutant combinations of neurotactin and other genes encoding adhesion/signaling molecules, including neuroglian, derailed, and kekkon1, displayed phenotypic synergy. This result provides evidence for functional cooperativity in vivo between the adhesion and signaling pathways controlled by neurotactin and the other three genes.