The growth cone is a growing nerve tip that actively elongates toward the target cells at which it transforms into the synapse. The active extension of the growth cone is accompanied by expansion of the surface membrane that is probably mediated by the membrane fusion between the surface membrane and that of vesicles in the growth cone. By using F-actin overlay assay, we have recently found four proteins and named them as Neurabin I,Neurabin II,Afadin, and AF-6, which have one PDZ domain and are localized at synapses. Introduction of Neurabin I antisense RNA in neurons resulted in inhibition of neurite outgrowth. Afadin and AF-6 were localized at both adherens junctions and synapses. These results suggests that Neurabin I,Neurabin II,Afadin, and AF-6 may function as new adhesive systems at both adherens junctions and synapses. We have also found a new protein, Tomosin, which binds to syntaxin and may regulate the membrane fusion machinery in synapses as well as in the growth cones.