Organic solvent extraction as a versatile procedure to identify hydrophobic chloroplast membrane proteins.
As a complementary approach to genome projects, proteomic analyses have been set up to identify new gene products. One of the major challenges in proteomics concerns membrane proteins, especially the minor ones. A procedure based on the differential extraction of membrane proteins in chloroform/methanol mixtures, was tested on the two different chloroplast membrane systems: envolope and thylakoid membranes. Combining the use of classical sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry analyses, this procedure enabled identification of hydrophobic proteins. The propensity of hydrophobic proteins to partition in chloroform/methanol mixtures was directly correlated with the number of amino acid residues/number of putative transmembrane regions (Res/TM ratio). Regardless of the particular case of some lipid-interacting proteins, chloroform/methanol extractions allowed enrichment of hydrophobic proteins and exclusion of hydrophilic proteins from both membrane systems, thus demonstrating the versatility of the procedure.
Ferro
M
M
Département de Biologie Moléculaire et Structurale, CEA-Grenoble, France.
Seigneurin-Berny
D
D
Rolland
N
N
Chapel
A
A
Salvi
D
D
Garin
J
J
Joyard
J
J
D002736:Chloroplasts / Q000737:chemistry*; D003902:Detergents; D004591:Electrophoresis, Polyacrylamide Gel; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000737:chemistry*; D009930:Organic Chemicals; D012492:Salts; D012995:Solubility; D012997:Solvents
D003902:Detergents; D008565:Membrane Proteins; D009930:Organic Chemicals; D012492:Salts; D012997:Solvents