Identification of the N-termini of NADPH : protochlorophyllide oxidoreductase A and B from barley etioplasts (Hordeum vulgare L.)

FEBS J. 2009 Feb;276(4):1074-81. doi: 10.1111/j.1742-4658.2008.06850.x. Epub 2009 Jan 16.


The N-termini of the NADPH : protochlorophyllide oxidoreductase (POR) proteins A and B from barley and POR from pea were determined by acetylation of the proteins and selective isolation of the N-terminal peptides for mass spectrometry de novo sequence analysis. We show that the cleavage sites between the transit peptides and the three mature POR proteins are homologous. The N-terminus in PORA is V48, that in PORB is A61, and that in POR from pea is E64. For the PORB protein, two additional N-termini were identified as A62 and A63, with decreased signal intensity of the corresponding N-terminal peptides. The results show that the transit peptide of PORA is considerably shorter than previously reported and predicted by ChloroP. A pentapeptide motif that has been characterized as responsible for binding of protochlorophyllide to the transit peptide of PORA [Reinbothe C, Pollmann S, Phetsarath-Faure P, Quigley F, Weisbeek P & Reinbothe S (2008) Plant Physiol148, 694-703] is shown here to be part of the mature PORA protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Amino Acid Sequence
  • Binding Sites
  • Chloroplasts / enzymology*
  • Hordeum / enzymology*
  • Molecular Sequence Data
  • Oxidoreductases Acting on CH-CH Group Donors / chemistry*
  • Oxidoreductases Acting on CH-CH Group Donors / metabolism
  • Plant Proteins / chemistry*
  • Plant Proteins / metabolism
  • Tandem Mass Spectrometry


  • Plant Proteins
  • Oxidoreductases Acting on CH-CH Group Donors
  • protochlorophyllide reductase