Predicted to enable serine-type endopeptidase inhibitor activity. Involved in several processes, including anatomical structure morphogenesis; distal tip cell migration; and nematode larval development. Located in basement membrane. Expressed in several structures, including CAN; GLR; basal lamina; enteric muscle; and somatic gonad precursor. Is an ortholog of human PAPLN (papilin, proteoglycan like sulfated glycoprotein).