Membrane trafficking in higher plant cells: GFP and antibodies, partners for probing the secretory pathway

Eukaryotic cells are characterised by the organised distribution of membran e bounded compartments in their cytoplasm. The endoplasmic reticulum (ER) a nd the Golgi apparatus (GA) are part of this endomembrane machinery. They a re involved in protein flow, and are in charge of specific functions such a s the assembly, sorting and transport of newly synthesised proteins, glycop roteins or polysaccharides to their final destination, where the macromolec ules are recognised either for action, storage, deposition or degradation. The structural and functional relationship between the ER and GA in higher plants is still a matter of debate. Therefore, it was essential to develop probes that would specifically label proteins or glycoproteins of the endom embrane system in situ. Here we compare two complementary approaches to pro be plant endomembranes; immunocytochemistry on fixed cells, and in vivo stu dies using the expression of GFP tagged chimeric proteins. The structural r elationship between ER and GA as based on pharmacological approaches using the two systems is explored. (C) Societe francaise de biochimie et biologie moleculaire / Elsevier, Paris.