PLANT PHYSIOLOGY , Vol 109, Issue 3 1007-1016, Copyright © 1995 by American Society of Plant Biologists
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BIOCHEMISTRY AND ENZYMOLOGY |
Fractionation and Structural Characterization of Arabinogalactan-Proteins from the Cell Wall of Rose Cells
M. D. Serpe and E. A. Nothnagel
Department of Bo tany and Plant Sciences, University of California, Riverside, California 92521-0124
Arabinogalactan-proteins (AGPs) have been purified from Paul's Scarlet rose
(Rosa sp.) cell walls. As estimated by gel permeation chromatography, the
apparent molecular masses of the two major cell-wall AGP fractions were 130
and 242 kD. Since the 130-kD AGP had a ratio of arabinose/glucuronic acid
that was 12 times higher than that of the 242-kD AGP, the fractions were
named cell-wall AGP1 (CW-AGP1) and glucuronogalactan-protein (GGP),
respectively. CW-AGP1 and GGP contained predominantly t-arabinofuranosyl
residues; 3-linked, 6-linked, and 3,6-branched galactopyranosyl residues;
and 4-linked and t-glucuronopyranosyl residues. The 1H-nuclear magnetic
resonance spectra of CW-AGP1 and GGP showed that the arabinofuranosyl and
galactopyranosyl residues were predominantly in [alpha]- and
[beta]-anomeric configuration, respectively, and that GGP contained a few
O-acetyl residues. The protein moieties of CW-AGP1 and GGP were both rich
in hydroxyproline and alanine but differed in the percentage of various
amino acids, including hydroxyproline, alanine, serine, and glycine.
Cell-wall AGPs bound to ([beta]-D-glucosyl)3 Yariv phenylglycoside, but the
stoichiometry of binding was about 6 times greater in GGP than in other
Rosa AGPs. GGP seems to be peculiar to the cell wall, since no similar
molecule was found in the culture medium.
