THE BIOLOGICAL ROLES OF SERINE AND CYSTEINE PROTEINASE INHIBITORS IN PLANTS1

ABSTRACT- Proteinase inhibitors are proteins widely distributed in plants. Among these, the serine proteinase inhibitors, of which trypsin inhibitors are the most studied, are thought to participate in the array of defensive substances that plants synthesize for protection against pest and pathogens. Cysteine proteinase inhibitors, of which papain inhibitors are the most well known, have been recently associated, on the other hand, with the control of protein mobilization. In this review I discuss recent findings that favor these views. Additional index terms: trypsin inhibitors, papain inhibitors, seeds, defense proteins.