The PLAC (protease and lacunin) domain is a short six-cysteine region that is usually found at the C terminal of proteins. It is found in a range of proteins including PACE4 (paired basic amino acid cleaving enzyme 4) and the extracellular matrix protein lacunin [1].

1: Expression of lacunin, a large multidomain extracellular matrix protein, accompanies morphogenesis of epithelial monolayers in Manduca sexta. Nardi JB, Martos R, Walden KK, Lampe DJ, Robertson HM; Insect Biochem Mol Biol. 1999;29:883-897. PMID:10528409