PMAP-36 is a cathelicidin-derived host defence peptide originally deduced by a transcript from pig bone marrow RNA. The expression of the propep-tide in leukocytes, and the structure, antimicrobial activity, and mechanism of action of the mature peptide were investigated. The proform is stored as a dimeric precursor of 38 kDa formed by a dimerization site at its C-ter-minal cysteine residue; it is likely that the mature peptide is dimeric when released.