Enables syntaxin-1 binding activity and syntaxin-3 binding activity. Acts upstream of or within cellular response to interferon-gamma and exocytosis. Located in apical plasma membrane; phagocytic vesicle; and zymogen granule membrane. Is expressed in several structures, including brain; gut; respiratory system; sensory organ; and urinary system. Human ortholog(s) of this gene implicated in familial hemophagocytic lymphohistiocytosis 5. Orthologous to human STXBP2 (syntaxin binding protein 2). [provided by Alliance of Genome Resources, Apr 2022]