Journal Article

Pumpkin Peroxisomal Ascorbate Peroxidase is Localized onPeroxisomal Membranes and Unknown MembranousStructures

Kazumasa Nito, Katsushi Yamaguchi, Maki Kondo, Makoto Hayashi and Mikio Nishimura

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 42, issue 1, pages 20-27
Published in print January 2001 | ISSN: 0032-0781
Published online January 2001 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pce003
Pumpkin Peroxisomal Ascorbate Peroxidase is Localized onPeroxisomal Membranes and Unknown MembranousStructures

More Like This

Show all results sharing these subjects:

  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

To investigate the roles of peroxisomal membrane proteins in the reversible conversion of glyoxysomes to leaf peroxisomes, we characterized several membrane proteins of glyoxysomes. One of them was identified as an ascorbate peroxidase (pAPX) that is localized on glyoxysomal membranes. Its cDNA was isolated by immunoscreening. The deduced amino acid sequence encoded by the cDNA insert does not have a peroxisomal targeting signal (PTS), suggesting that pAPX is imported by one or more PTS-independent pathways. Subcellular fractionation of 3- and 5-d-old cotyledons of pumpkin revealed that pAPX was localized not only in the glyoxysomal fraction, but also in the ER fraction. A magnesium shift experiment showed that the density of pAPX in the ER fraction did not increase in the presence of Mg2+, indicating that pAPX is not localized in the rough ER. Immunocytochemical analysis using a transgenic Arabidopsis which expressed pumpkin pAPX showed that pAPX was localized on peroxisomal membranes, and also on a unknown membranous structure in green cotyledons. The overall results suggested that pAPX is transported to glyoxysomal membranes via this unknown membranous structure.

Keywords: Key words: Ascorbate peroxidase — Endoplasmic reticulum — Hydrogen peroxide — Peroxisome — Protein transport — Pumpkin.; Abbreviations: cAPX, cytosolic ascorbate peroxidase; pAPX, peroxisomal ascorbate peroxidase; BiP, binding protein; CAT, catalase; ER, endoplasmic reticulum; HPR, hydroxypyruvate reductase; ICL, isocitrate lyase; PTS, peroxisome targeting signal.

Journal Article.  5610 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.