Plays a significant role in nervous system function, which is subtle at the cellular level but manifests itself in complex behavior. Identified in a complex with Syt1 and nwk. Widely expressed in the embryonic and adult nervous system synaptic terminals. Detected at all developmental stages after mid-embryogenesis. Mutants show no obvious defects in brain morphology and no striking qualitative changes in behavior are observed. Quantitative differenes are seen: mutants show faster habituation of an olfactory jump response, enhanced ethanol tolerance, and significant defects in learning and memory as measured using three different paradigms. Readthrough of the terminator UGA may occur between the codons for 581-Met and 583-Glu. Belongs to the synapsin family.