In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 98, No. 9 ( 2001-04-24), p. 5353-5358
Abstract:
The ricinosome (synonym, precursor protease vesicle) is a novel
organelle, found so far exclusively in plant cells. Electron microscopic studies suggest that it buds off from the endoplasmic
reticulum in senescing tissues. Biochemical support for this unusual origin now comes from the composition of the purified organelle, which
contains large amounts of a 45-kDa cysteine endoprotease precursor with a C-terminal KDEL motif and the endoplasmic reticulum lumen residents
BiP (binding protein) and protein disulfide isomerase. Western blot analysis, peptide sequencing, and mass spectrometry demonstrate
retention of KDEL in the protease proform. Acidification of isolated ricinosomes causes castor bean cysteine endopeptidase activation, with
cleavage of the N-terminal propeptide and the C-terminal KDEL motif. We propose that ricinosomes accumulate during senescence by programmed
cell death and are activated by release of protons from acidic vacuoles.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.061038298
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2001
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
