Table III.

Identification of SSIIIHD-binding proteins by mass spectrometry

BandIdentified ProteinProtein FamilyAccession No.Unique PeptidesPredicted Molecular MassaObserved Molecular Massb
kD
aUnknowncChloroplast HSP70-11523377937774
aSBEIIbMaize branching enzyme IIb116991129173
bUnknowncStromal HSP7011548799887472
3PPDK1Maize pyruvate orthophosphate dikinase19380635716d95e95
3PPDK2Maize pyruvate orthophosphate dikinaseTA164186_457712f9595
4SUS-SH1Sucrose synthase (sh1 gene)135060129285
4PPDK2Maize pyruvate orthophosphate dikinaseTA164186_45772g95e85
5PPDK2Maize pyruvate orthophosphate dikinaseTA164186_45772g95e70
6SH2ADPGlc pyrophosphorylase large subunit (sh2 gene)170792475757
6PPDK2Maize pyruvate orthophosphate dikinase627381116h95e57
6SSIIIHDMaize starch synthase III homology domain3057120418857
  • a Molecular mass values of full-length proteins are indicated (i.e. before removal of plastid or other targeting sequences), unless otherwise indicated.

  • b Observed molecular mass values were estimated based on comparison with those of known standard proteins (Fig. 6B).

  • c Unknown proteins are those for which maize cDNA or genomic DNA sequences are not yet included in the public data set. Protein family assignment is made based on exact matches between the peptide sequences and known protein sequences from rice or Arabidopsis, together with BLAST analysis to identify related proteins in other species.

  • d Seven peptides are perfect matches with PPDK1, and nine are perfect matches with both PPDK1 and PPDK2.

  • e Predicted molecular mass is for the mature protein after cleavage of the plastid-targeting peptide.

  • f Six peptides are perfect matches with PPDK2, and six are perfect matches with both PPDK1 and PPDK2.

  • g One peptide is a perfect match with PPDK2, and one is a perfect match with both PPDK1 and PPDK2.

  • h Three peptides are perfect matches with PPDK2, and three are perfect matches with both PPDK1 and PPDK2.