NOVEL GENE FAMILIES INVOLVED IN NEURAL PATHFINDING

Recent studies have uncovered a bifunctional role of the diffusible ax on guidance molecules netrin-1 and UNC-6 in that they attract some axo ns and steer others away simultaneously. Homology screens have extende d the semaphorin and collapsin family to include at least 20 members, in both secreted and membrane-bound forms. Eph-related receptors and t heir membrane-bound ligands, the function of which have only been char acterized poorly to date, have been added to the growing number of mol ecules involved in axon guidance and fasciculation.