Figure 3. Domain structure of prtP-encoded lactocepin. PrtP-encoded lactocepins from lactobacilli and lactococci are highly similar but show different substrate specificities even within the same species. It has been found that the catalytic domain (PR), the insertion domain (I) and the A domain play a role in the casein specificity of certain prtP-encoded lactocepins. However, it is not known which residues of the active secreted protease (PR to H domain) determine the anti-inflammatory substrate profile of L.p-derived prtP-encoded lactocepin.