Membrane protein quantifying

Patent Granted It is intended to provide a method whereby a membrane protein occurring in cell membrane can be conveniently, quickly and highly accurately quantified by mass spectrometry with the use of a stable isotope-labeled peptide as a probe. This method comprises: fragmenting a cell membrane protein into oligopeptide fragments; identifying them by LC-MSMS; selecting peptides obtained by using a protease and a peptide specific for the target molecule as essential criteria; setting scored criteria for selection considering hydrophobic amino acid content, sequential conditions, amino acid residue count, specific amino acid sequential conditions and so on.