A proteomic analysis of organelles from Arabidopsis thaliana

We introduce the use of Arabidopsis thaliana callus culture as a system for proteomic analysis of plant organelles using liquid-grown callus. This cal lus is relatively homogeneous, reproducible and cytoplasmically rich, and p rovides organelles in sufficient quantities for proteomic studies. A databa se was generated of mitochondrial, endoplasmic reticulum (ER), Golgi/prevac uolar compartment and plasma membrane (PM) markers using two-dimensional so dium dodecyl sulphate-polyacrylamide gel electrophoresis (2-D SDS-PAGE) and peptide sequencing or mass spectrometric methods. The major callus membran e-associated proteins were characterised as being integral or peripheral by Triton X-114 phase partitioning. The database was used to define specific proteins at the Arabidopsis callus plasma membrane. This database of organe lle proteins provides the basis for future characterisation of the expressi on and localisation of novel plant proteins.