Enables serine-type endopeptidase inhibitor activity. Involved in positive regulation of neuron projection development and regulation of cell adhesion. Predicted to be located in neuronal cell body and secretory granule lumen. Predicted to be active in extracellular space. Human ortholog(s) of this gene implicated in familial encephalopathy with neuroserpin inclusion bodies. Orthologous to human SERPINI1 (serpin family I member 1). [provided by Alliance of Genome Resources, Apr 2022]