Enables cysteine-type endopeptidase inhibitor activity and protease binding activity. Involved in several processes, including negative regulation of T cell proliferation; positive regulation of cell population proliferation; and regulation of protein metabolic process. Located in extracellular space; intracellular membrane-bounded organelle; and perikaryon. Human ortholog(s) of this gene implicated in high molecular weight kininogen deficiency. Orthologous to human KNG1 (kininogen 1). [provided by Alliance of Genome Resources, Apr 2022]