Enables neurexin family protein binding activity. Involved in regulation of synaptic vesicle exocytosis. Acts upstream of or within calcium ion import; positive regulation of calcium ion import; and positive regulation of transcription by RNA polymerase II. Located in several cellular components, including basolateral plasma membrane; cell-cell junction; and cytosol. Is active in Schaffer collateral - CA1 synapse. Colocalizes with basement membrane. Is expressed in several structures, including alimentary system; genitourinary system; integumental system; nervous system; and sensory organ. Human ortholog(s) of this gene implicated in FG syndrome and syndromic X-linked intellectual disability Najm type. Orthologous to human CASK (calcium/calmodulin dependent serine protein kinase). [provided by Alliance of Genome Resources, Apr 2022]