Structure of the glycosylphosphatidylinositol anchor of an arabinogalactan protein from Pyrus communis suspension-cultured cells

AUTOR(ES)

Oxley, David

FONTE

The National Academy of Sciences

RESUMO

Arabinogalactan proteins (AGPs) are proteoglycans of higher plants, which are implicated in growth and development. We recently have shown that two AGPs, NaAGP1 (from Nicotiana alata styles) and PcAGP1 (from Pyrus communis cell suspension culture), are modified by the addition of a glycosylphosphatidylinositol (GPI) anchor. However, paradoxically, both AGPs were buffer soluble rather than membrane associated. We now show that pear suspension cultured cells also contain membrane-bound GPI-anchored AGPs. This GPI anchor has the minimal core oligosaccharide structure, d-Manα(1–2)-d-Manα(1–6)-d-Manα(1–4)-d-GlcN-inositol, which is consistent with those found in animals, protozoa, and yeast, but with a partial β(1–4)-galactosyl substitution of the 6-linked Man residue, and has a phosphoceramide lipid composed primarily of phytosphingosine and tetracosanoic acid. The secreted form of PcAGP1 contains a truncated GPI lacking the phosphoceramide moiety, suggesting that it is released from the membrane by the action of a phospholipase D. The implications of these findings are discussed in relation to the potential mechanisms by which GPI-anchored AGPs may be involved in signal transduction pathways.

Documentos Relacionados

• Protein isoprenylation in suspension-cultured tobacco cells.
• A Novel Hydroxyproline-Deficient Arabinogalactan Protein Secreted by Suspension-Cultured Cells of Daucus carota (Purification and Partial Characterization).
• Molecular cloning of a gene encoding an arabinogalactan-protein from pear (Pyrus communis) cell suspension culture.
• Changes in Protein Isoprenylation during the Growth of Suspension-Cultured Tobacco Cells.
• Characterization of a H+ Efflux from Suspension-cultured Plant Cells 1