Table 1.

Overview of selected protein profiling technologies

Technology	Type of labeling required	Ability to detect many post-translational modifications	Biomolecules that are optimally quantified	Approximate dynamic range (and reference)	Number of proteins/spots quantified (and reference)
Two-dimensional gel electrophoresis	Silver staining	Yes	Naturally occurring forms of proteins larger than 10 kDa	10 [9]	1,500 [8]
Differential two-dimensional fluorescence gel electrophoresis (DIGE)	In vitro with Cy2, Cy3 or CY5 fluorophores at primary amines	Yes	Naturally occurring forms of proteins larger than 10 kDa	10,000 [9]	1,100 [51]
SELDI- or MALDI-MS disease biomarker discovery	None	Yes	Naturally occurring forms of proteins smaller than 10 kDa	25	Not applicable
Isotope-coded affinity tag (ICAT) - LC/MS	In vitro with H1/D or C12/C13 ICAT reagent at cysteine	No	Cysteine-containing tryptic peptides from digests of protein extracts	10,000*	496 [18]
N14/N15 - LC/MS	In vivo at nitrogens in amino acids	Yes	Tryptic peptides from digests of protein extracts	10,000 [19]	872 [20]

*Assumed to be similar to that for multidimensional protein identification. Abbreviations: SELDI-MS, surface-enhanced laser desorption ionization mass spectrometry; MALDI-MS, matrix-assisted laser desorption ionization mass spectrometry; LC/MS, liquid chromatography and mass spectrometry.