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Isolation and characterization of cDNA clones encoding jacalin isolectins
1Department of Biotechnology Plant Breeding Division, Pioneer Hi-Bred International, Johnston, Iowa 50131.
The Journal of Biological Chemistry
|March 15, 1993
Summary
Multiple jacalin isolectins exist in jackfruit seeds, initially synthesized as a prepropeptide. This precursor protein contains distinct regions, suggesting a complex processing pathway into mature subunits.
Area of Science:
- Molecular Biology
- Biochemistry
- Plant Science
Background:
- Jacalins are lectins found in Artocarpus integrifolia (jackfruit) seeds.
- Lectins play roles in various biological processes, including cell recognition and immune responses.
Purpose of the Study:
- To investigate the molecular characteristics of jacalin isolectins from jackfruit seeds.
- To elucidate the precursor structure and processing of jacalin.
Main Methods:
- Isolation and sequencing of jacalin cDNA clones from a jackfruit seed library.
- Deduced amino acid sequence analysis of jacalin precursors.
- Western blot analysis of jackfruit seed extract.
- Immunoprecipitation of in vitro translated products.
Main Results:
- Four jacalin cDNA clones (pSKcJA1, pSKcJA3, pSKcJA15, pSKcJA17) were identified, sharing high sequence homology (>94%).
- Deduced sequences revealed multiple jacalin isolectins synthesized as a prepropeptide with a specific domain structure (N-signal, propeptide, beta-peptide, linker, alpha-peptide).
- Western blot and immunoprecipitation confirmed the prepropeptide structure and suggested complex processing into mature alpha- and beta-subunits.
Conclusions:
- Jackfruit seeds contain multiple jacalin isolectins.
- Jacalin is synthesized as a prepropeptide, with the propeptide likely aiding in protein folding.
- The unusual structure indicates a unique processing mechanism for this lectin precursor.