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Figure 1 | Genome Biology

Figure 1

From: Comparing cellular proteomes by mass spectrometry

Figure 1

Quantitative MS-based proteomics. (a) Analysis of complex peptide mixtures by LC-MS2. Peptide mixtures are resolved by liquid chromatography, ionized through electrospray and resolved by MS1. Selected peptides are fragmented by collision with an inert gas and the resulting MS2 spectra are recorded. (b) Quantitative proteomics strategies. In the SILAC technique, isotope-labeled peptide intensities (I) are compared in the MS1 spectra. For 'label-free' quantitation, intensities of peptides are compared between different runs. Alternatively, standard peptides are spiked into the mixture to yield calibration for absolute peptide abundances. R refers to the ratio between either heavy and light peptides (SILAC panel) or ion intensities between different runs (label-free quantitation).

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