Background

Plasma membrane (PM) proteins participate in diverse biological processes including signal transduction, ion transport and membrane trafficking, and are the first responders in cell-environment communication. They have a complicated composition varying from species, cell types and developmental stages (Alexandersson et al., 2008). Revealing their components and the expression features comprehensively with mass spectrometry (MS) is of great importance for developmental biology. However, their hydrophobic nature and the low abundance are a big challenge for the proteomic analysis (Wu and Yates, 2003). Additives like normal surfactants, organic solvents and urea are often used to improve PM proteins’ solubility, but they will reduce the proteases’ activities and create ion suppression during MS analysis (Zhang, 2015). RapiGest SF is a novel acid-labile anionic surfactant, which is structurally and functionally similar to SDS but does not inhibit the common endopeptidases activities at low concentration (0.1% w/v). Thus RapiGest SF used in solubilizing PM proteins can not only facilitate their digestion by exposing cleavage sites but is also easily quenched by strong acid and removed through centrifugation so that the surfactant does not affect the MS identification (Yu et al., 2003). Peptides yield by the RapiGest SF-assisted digestion can directly undergo the strong cation exchange (SCX) fractionation (Yang and Wang, 2017), so that the low abundance peptides can be detected by the MS.