Abstract
A proteomic approach was developed for the identification of membrane-bound proteins of Arabidopsis thaliana. A vacuolar membrane-enriched fraction was prepared and washed to remove peripheral membrane proteins. The remaining membrane-bound proteins were subjected to SDS-PAGE and digested within gel slices with lysylendopeptidase. The resulting peptides were separated by reversed-phase HPLC and subjected to Edman sequencing. From the 163 peptide peaks analyzed, 69 peptide sequences were obtained, 64 of which were informative. The proteins corresponding to these peptide sequences were identified as 42 families by comparison with the genome. A total of 34 proteins was identified definitively with protein-specific peptide sequences. The detected transmembrane proteins included transporters, channels, receptors, and unknown molecules, whereas the remaining proteins included small GTPases, GTPase binding proteins, HSP 70-like proteins, ribosomal proteins, and unknown proteins. These membrane-anchored proteins are likely attached to membranes by hydrophobic anchor molecules or through tight association with other membrane-bound proteins.
