Predicted to enable cysteine-type endopeptidase inhibitor activity. Predicted to be involved in androgen receptor signaling pathway; defense response to Gram-negative bacterium; and killing of cells of other organism. Predicted to be located in extracellular region. Predicted to be active in several cellular components, including nucleus; sperm flagellum; and sperm head. Orthologous to human CST11 (cystatin 11). [provided by Alliance of Genome Resources, Apr 2022]