Enables actin binding activity and cyclin-dependent protein serine/threonine kinase activator activity. Acts upstream of or within nervous system development; positive regulation of calcium ion-dependent exocytosis; and positive regulation of protein kinase activity. Located in cytoplasm. Is expressed in several structures, including nervous system and retina. Orthologous to human CDK5R2 (cyclin dependent kinase 5 regulatory subunit 2). [provided by Alliance of Genome Resources, Apr 2022]