Enables protease binding activity. Involved in lipopolysaccharide-mediated signaling pathway; positive regulation of immune response; and proteolysis. Acts upstream of or within several processes, including B-1 B cell differentiation; cellular response to lipopolysaccharide; and positive regulation of NF-kappaB transcription factor activity. Located in cytosol. Part of polkadots. Is expressed in nervous system and neural retina. Human ortholog(s) of this gene implicated in immunodeficiency 12; lymphoma; and non-Hodgkin lymphoma. Orthologous to human MALT1 (MALT1 paracaspase). [provided by Alliance of Genome Resources, Apr 2022]