1 •1 Membrane and Cell Wall •Katerina Dadakova, Department of Biochemistry •Figures adopted from Buchanan et al., Biochemistry & molecular biology of plants 2 Plant membrane Membrane and Cell Wall c01_Figure9.JPEG 3 Plant membrane lipids Membrane and Cell Wall 4 Plant membrane lipids Membrane and Cell Wall c01_Figure4.JPEG 5 Plasma membrane Membrane and Cell Wall •Transport of molecules H+-ATPase, aquaporins,... •Signal transduction receptors •Cell wall synthesis cellulose synthase, callose synthase c01_Figure12.JPEG Plasmodesma PM, plasma membrane ER, endoplasmic reticulum CW, cell wall 6 Membrane transport Membrane and Cell Wall Membrane transport systems: •Pumps •Channels •Cotransporters • •Nutrient acquisition •Metabolite distribution •Compartmentalization of metabolites • •Energy transduction • •Turgor generation • •Waste product excretion • •Signal transduction ATP ADP+P H+ K+ H+ Sucrose 7 Transmembrane electrochemical potential Membrane and Cell Wall Electrochemical potential: •concentration •charge •membrane voltage • 8 H+ pumps Membrane and Cell Wall 9 ABC-type pumps Membrane and Cell Wall A glutathione-conjugated xenobiotic and a chlorophyll catabolite • ATP-binding cassette transporter 10 Ion channels Membrane and Cell Wall Ion channels are: •passive •selective (to some degree) •regulated Activity of channels in tonoplast. The prevalence of open state is influenced by membrane voltage. O1,2, or 3 is the number of channels open. 11 Cotransporters Membrane and Cell Wall Transport process mechanisms 12 Aquaporins Membrane and Cell Wall Plant membranes are highly permeable for water The direction of water transport across membranes is determined by hydrostatic and osmotic pressures. 13 Cell-to-cell transport Membrane and Cell Wall Intercellular transport can occur along apoplastic, symplastic, and transcellular routes Long-distance transport follows two pathways: xylem and phloem 14 Cell wall Membrane and Cell Wall 15 Cell wall sugars Membrane and Cell Wall 16 Cell wall polysaccharides Membrane and Cell Wall Plasma memrane Cellulose synthase UDP UDP-Glucose Sucrose synthase Cytosol Extracellular space Cellulose Sucrose Fructose Crosslinking glycans and pectin polymers Membrane and Cell Wall Cellulose Pectins Cell wall proteins Callose Crosslinking glycans Middle lamela Pectin Cellulose microfibril Crosslinking glycans Cell wall architecture Membrane and Cell Wall Cell growth Vessel elements Secondary wall Membrane and Cell Wall Monolignols