Large scale characterization of plant plasma membrane proteins

After a brief review of the strategies used to date to identify systematica lly plasma membrane (PM) proteins, emphasis was given to the proteomic appr oach of PM proteins from the model plant Arabidopsis thaliana. Comparative analysis of two-dimensional gels from PM and cytosolic fractions was used t o assess the cellular origin of proteins found in PM fraction. The classifi cation obtained was confirmed by protein sequencing that showed, in additio n, that most analyzed proteins were peripheral proteins. A large proportion of these appeared to correspond to PM-constitutive proteins that were pres ent in the PM from different plant organs, but were not uniquely located at the PM depending on the organ. In addition, the presence of organ-specific sets of PM-specific proteins was also demonstrated. Additional procedures were developed to identify integral PM proteins. The combined use of PM was hes with alkaline carbonate buffer or Triton X-100/KBr, and of a new deterg ent to solubilize protein, resulted in improved recovery of hydrophobic pro teins on gels. Results are discussed in terms of construction of comprehens ive proteomes for PM and other membranes and organelles. (C) Societe franca ise de biochimie et biologie moleculaire / Elsevier, Paris.