PLANT PHYSIOLOGY , Vol 108, Issue 3 1001-1012, Copyright © 1995 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Secondary Cell-Wall-Specific Glycoprotein(s) from French Bean Hypocotyls
P. Wojtaszek and G. P. Bolwell
Division of Biochemistry, School of Biological Sciences, Royal Holloway and Bedford New College, University of London, Egham, Surrey TW20 0EX, United Kingdom
Specific labeling of secondary cell walls of tracheary elements and of
xylary and phloem fibers has been observed when wheat germ agglutinin (WGA)
and anti-WGA antibodies were used during ultrastructural studies of French
bean (Phaseolus vulgaris L.) hypocotyls. In this report we demonstrate that
at least part of this labeling is due to the presence of secondary
cell-wall-specific glycoproteins. Three major novel glycoproteins with
relative molecular weights of 55,000, 86,000, and 90,000, purified by means
of WGA-Sepharose affinity chromatography, have been characterized. Their
amino acid composition indicates that they are not the members of known
classes of structural cell-wall proteins, since they contain no
hydroxyproline, a lower level of glycine than seen in glycine-rich
proteins, and very little proline. N-terminal sequences of all three
proteins show no significant homology with other proteins. Antibodies were
raised against electrophoretically pure 90-kD glycoprotein. These were used
to localize this protein in secondary cell walls of xylem tracheary
elements and in xylary and phloem fibers, i.e. in the same compartments
where labeling with WGA has been observed. To our knowledge this is one of
the first biochemical and ultrastructural demonstrations of secondary
cell-wall-specific glycoproteins.
