Fig. 8.
High-resolution LC-MS workflow for sequencing picomole quantities of transmembrane proteins from biological samples. Pentameric GABAA receptors were purified from an immunoaffinity column. The proteins were denatured and delipidated followed by timed, in-solution digestion with several proteolytic enzymes. Peptide recovery was enhanced using sequential solid phase extraction. Peptide identification and sequencing was optimized using nano-LC-ESI-MS with high resolution in both MS1 and MS2 spectra.