Related Experiment Video
Updated: Jul 29, 2026

Structural Characterization of Mannan Cell Wall Polysaccharides in Plants Using PACE
Published on: October 16, 2017
Gum arabic glycoprotein contains glycomodules of both extensin and arabinogalactan-glycoproteins
L J Goodrum1, A Patel, J F Leykam
1Ohio State University School of Ophthalmology, Columbus, USA.
Abstract:
Gum arabic glycoprotein (GAGP) is a large molecular weight, hydroxyproline-rich arabinogalactan-protein (AGP) component of gum arabic. GAGP has a simple, highly biased amino acid composition indicating a repetitive polypeptide backbone. Previous work (Qi, W., Fong, C., Lamport, D.T.A., 1991. Plant Physiology 96, 848), suggested small (approximately 11 residue) repetitive peptide motifs each with three Hyp-arabinoside attachment sites and a single Hyp-arabinogalactan polysaccharide attachment site. We tested that hypothesis by sequence analysis of the GAGP polypeptide after HF-deglycosylation. A family of closely related peptides confirmed the presence of a repetitive 19-residue consensus motif. However, the motif: Ser-Hyp-Hyp-Hyp-Thr-Leu-Ser-Hyp-Ser- Hyp-Thr-Hyp-Thr-Hyp-Hyp-Leu-Gly-Pro-His, was about twice the size anticipated. Thus, judging by Hyp-glycoside profiles of GAGP, the consensus motif contained six Hyp-arabinosides rather than three and two Hyp-polysaccharides rather than one. We inferred the glycosylation sites based on the Hyp contiguity hypothesis which predicts arabinosides on contiguous Hyp residues and arabinogalactan polysaccharides on clustered non-contiguous Hyp residues, i.e. the GAGP motif would consist of arabinosylated contiguous Hyp blocks flanking two central Hyp-polysaccharides. We predict this rigidifies the glycoprotein, enhances the overall symmetry of the glycopeptide motif, and may explain some of the remarkable properties of gum arabic.
Related Concept Videos
Protein Glycosylation
Glycosylation occurs in...
Oligosaccharide Assembly
Multiple sugar molecules that may or may...
Proteoglycans
Glycosaminoglycans
GAGS are found in the extracellular matrix of vertebrates, invertebrates, and bacteria. Due to their polar nature they attract water, and serve as excellent lubricants or shock absorbers in an animal body.
Hyaluronic...
Matrix Proteoglycans and Glycoproteins
Glycocalyx and its Functions
Components of...

