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Trypsin inhibitor polymorphism: multigene family expression and posttranslational modification
L Quillien1, E Ferrasson, D Molle
1Laboratoire de Biochimie et Technologie des Protéines, INRA Nantes, France.
Journal of Protein Chemistry
|April 1, 1997
Summary
Six trypsin inhibitors from winter pea seeds were purified and identified as members of the Bowman-Birk family. Isoforms arise from distinct gene expression and post-translational modifications, revealing complex protein diversity.
Area of Science:
- Plant biochemistry
- Molecular biology
- Protease inhibitor research
Background:
- Winter pea seeds contain multiple trypsin inhibitors.
- These inhibitors are structurally related and belong to the Bowman-Birk family.
Purpose of the Study:
- To purify and characterize trypsin inhibitors from winter pea seeds.
- To elucidate the relationships and isoform formation mechanisms among these inhibitors.
Main Methods:
- Purification of trypsin inhibitors.
- Amino acid composition and molecular mass determination.
- Peptide mapping after trypsin digestion.
- N-terminal sequencing.
Main Results:
- Six protease inhibitors (PSTI I-V) were purified from winter pea seeds.
- All inhibitors are closely related Bowman-Birk family members.
- Two isoforms (PSTI IVa, IVb) originate from different genes, with four amino acid differences.
- Two other isoforms (PSTI I, II) result from post-translational cleavage of PSTI IVa and IVb, respectively.
Conclusions:
- Winter pea trypsin inhibitors exhibit complex isoform diversity.
- Isoform generation involves both distinct gene expression and post-translational modifications.
- Understanding these mechanisms is crucial for plant protease inhibitor research.