UAS regulatory sequences drive expression of a membrane-tethered form of the Hsap\GCG ligand. The protein consists of Hsap\GCG, a flexible linker containing a Tag:MYC tag, the extracellular domain of Hsap\ICAM1, and the transmembrane and cytoplasmic domains of Nrx-1. The Hsap\GCG ligand sequence is a mutant form that has a high potency for activation of the Hsap\GCGR receptor. The protein is sized to extend across the average length of a synapse, is enriched in axons and is targeted to axon termini.