Glycosylinositol phosphorylceramides from Rosa cell cultures are boron-bridged in the plasma membrane and form complexes with rhamnogalacturonan II.
Bottom Line: Using high-voltage paper electrophoresis, we showed that addition of GIPCs decreased the electrophoretic mobility of radiolabelled RG-II, suggesting formation of a GIPC-B-RG-II complex.We conclude that B plays a structural role in the plasma membrane.Finally, our results suggest a role for GIPCs in the RG-II dimerization process.
Affiliation: The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, EH9 3JH, UK.Show MeSH
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Mentions: Using this extract, we investigated the ability of GIPC to bind RG-II by testing the effect of GIPC on the mobility of radiolabelled RG-II on paper electrophoresis. We incubated tracer quantities of [3H]RG-II with an excess of the purified GIPC under conditions suitable for RG-II dimerization (Chormova et al., 2013). On paper electrophoresis at pH 2.0, monomeric [3H]RG-II and the same preparation partially or fully dimerized by H3BO3, without or with 0.5 mm Pb2+ respectively, all migrated approximately 8 cm towards the anode (Figure4a). Thus dimeric RG-II had approximately 1.6× the charge of monomeric RG-II [estimated by application of Offord’s law, which states that mobility on paper electrophoresis is proportional to the Q:Mr2/3 ratio, where Q is the molecule’s net charge and where the molecular weight to the power of 2/3 is an indication of the molecule’s surface area (Offord, 1966; Fry, 2011)]. Co-migration of monomeric and dimeric RG-II is confirmed in Figure4b-ii,iii).
Affiliation: The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, EH9 3JH, UK.