title: Isolation and characterization of membranes from the cells of maize root tips.
abstract: A discontinuous sucrose density gradient was used to separate membrane fractions from a homogenate of maize root tips. Endoplasmic reticulum-, Golgi apparatus-, plasma membrane- and mitochondria-rich fractions were identified by their enzymic characteristics and by their appearance under the electron microscope. Maize roots were incubated in vivo with D-[U-14C]glucose, [Me-14C]choline chloride and diazotized [U-3H]sulphanilic acid. The pattern of incorporation of radioactivity into the various membrane fractions was investigated. Analyses of the polypeptide chains of the membrane fractions by SDS-polyacrylamide gel electrophoresis showed that the mitochondria-rich fraction had a different pattern of polypeptides from that of the other membrane fractions. The results are discussed in relation to the hypothesis of endomembrane flow and differentiation.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology / Q000648:ultrastructure; D002499:Centrifugation, Density Gradient; D002855:Chromatography, Thin Layer; D004591:Electrophoresis, Polyacrylamide Gel; D007425:Intracellular Membranes / Q000201:enzymology / Q000648:ultrastructure*; D008854:Microscopy, Electron; D010455:Peptides / Q000032:analysis; D010944:Plants / Q000201:enzymology / Q000648:ultrastructure*; D003313:Zea mays / Q000201:enzymology / Q000648:ultrastructure
chemical_list: D000596:Amino Acids; D010455:Peptides