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GrainGenes Reference Report: TPJ-13-191

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Reference
TPJ-13-191
Title
Synthesis, processing and export of cytoplasmic endo-beta-1,4-xylanase from barley aleurone during germination
Journal
The Plant Journal
Year
2001
Pages
191-204
Author
Caspers MPM
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Abstract
Summary: We have identified the major endo-beta-1,4-xylanase (XYN-1) in the aleurone of germinating barley grain, and show that it is expressed as a precursor of Mr 61500 with both N- and C-terminal propeptides. XYN-1 is synthesized as an inactive enzyme in the cytoplasm, and only becomes active at a late stage of germination when the aleurone ceases to secrete hydrolases. A series of processing steps, mediated in part by aleurone cysteine endoproteases, yields a mature active enzyme of Mr 34000. Processing and extracellular release of the mature enzyme coincide with the programmed cell death (PCD)-regulated disintegration of aleurone cells. We discuss the significance of delayed aleurone cell-wall degradation by endoxylanases in relation to the secretory capacity of the aleurone, and propose a novel role for aleurone PCD in facilitating the export of hydrolases
Keyword
aleurone
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