Proteinase Inhibitor Gene Families: Tissue Specificity and Regulation
Proteinase inhibtors are a multifamily group of proteins that are ubiquitous in nature (Laskowski, Jr. and Kato, 1984). Inhibitor proteins have been isolated that specifically inhibit each of the four known mechanistic classes of proteolytic enzymes, i. e. serine, thiol, aspartyl and metalloproteinases. Overall, the serine proteinase inhibitors comprise over ten unrelated protein families (Laskowski, Jr., 1986) that are found within the animal and plant kingdoms (Table 1). The functional role of these inhibitor proteins appears to be either to protect tissues or fluids from proteolysis by foreign proteases or to regulate the levels of proteases that are metabolically active in the tissues or fluids that they are associated with. The majority of proteinase inhibitor proteins that have been purified from plants have been inhibitors of serine endopeptidases such as the animal digestive enzymes trypsin, chymotrypsin and elastase or the bacterial proteinase subtilisin. In plants, the inhibitor proteins usually account for from 1 – 15 % or more of the proteins of various storage organs such as seeds and tubers (Ryan, 1974) and in some plant species, in leaves, in fruit, or in both (see below).
KeywordsLectin Gene Kunitz Trypsin Inhibitor Proteinase Inhibitor Gene Wild Tomato Species Soybean Kunitz Trypsin Inhibitor
Unable to display preview. Download preview PDF.
- Jofuku, D. K., Okamuro, J. K., Goldberg, R. B., in press. An embryo DNA binding protein that interacts with a soybean lectin gene upstream region.Google Scholar
- Laskowski, M., Jr., 1986: Protein inhibitors of serine proteinases-mechanism and classification. In: Nutritional and Toxicological Significance of Enzyme Inhibitors in Foods (ed. M. Freidman), pp. 1–17. Plenum, New York.Google Scholar
- Laskowski, M., Jr., Sealock, R. W., 1971: Protein proteinase inhibitors-molecular aspects. The Enzymes, Vol. III (P. Boyer, ed.), pp. 375–483. Academic Press, New York.Google Scholar
- Lee, J. S., Brown, W. E., Graham, J. S., Pearce, G., Fox, E., Dreher, T. W., Ahern, K. G., Pearson, G. D., Ryan, C. A., 1986: Molecular characterization and phylogenetic studies of a wound-inducible proteinase inhibitor gene in Lyco-persicon species. Proc. Natl. Acad. Sci. U.S.A. 83, 7277–7281.PubMedCrossRefGoogle Scholar
- Pearce, G., Liljegren, D., Ryan, C. A., in press. Isolation and characterization of proteinase Inhibitors I and II from fruit of a wild tomato species (Lycopersicum peruvianum).Google Scholar
- Rackis, J. J., 1980: Protease inhibitors: Physiological properties and nutritional significance. In Antinutrients and Natural Toxicants in Foods (R. L. Ory, ed.), pp. 203–238. Food and Nutrition Press Inc. Westport, Conn.Google Scholar
- Ryan, C. A., 1978: Proteinase inhibitors in plant leaves: A biochemical model for pest-induced natural plant protection. TIBS 5, 148–151.Google Scholar
- Ryan, C. A., 1984: The defense mechanisms in plants. In: Plant Gene Research (E. S. Dennis, B. Hohn, Th. Hohn, P. King, J. Schell, D. P. S. Verma, eds.), pp. 375–386. Wien — New York: Springer-Verlag.Google Scholar
- Ryan, C. A., Pearce, G., An, G., Thornburg, R., in press. The regulation of expression of proteinase inhibitor genes in food crops. Acta Horticulturae.Google Scholar
- Sanchez-Sorrano, J. J., Keil, M., O’Connor, A., Schell, J., Willmitzer, L., 1987: Wound-induced expression of a potato proteinase inhibitor II gene in transgenic tobacco plants. EMBO J. 6, 303–306.Google Scholar
- Wilson, K., 1986: Role of proteolytic enzymes in the mobilization of protein reserves in the germinating dicot seed. In: Plant Proteolytic Enzymes, Vol. II (M. J. Dalling, ed.), pp. 411–468. CRC Press, Inc., Boca Raton, Fla.Google Scholar