Table 1 Quantitative proteomic techniques that have been applied to clinical proteomics using labeling method

2D-DIGE

Gel-based

Cy2, Cy3, Cy5, IC3-OSu, IC5-OSu

Most frequently used gel-based method

2 samples

[14], [15]

cICAT

Non-gel based

¹²C-ICAT (light)

¹³C-ICAT (heavy)

Labeled to cysteine thiol group

Most frequently used isotope labeling method

2 samples

[16]

SILAC

Non-gel based

¹²C- or ¹⁴N-lysine and arginine (light)

¹³C- or ¹⁵N-lysine and arginine (heavy)

Incorporated into cultured cells

Pre-labeling method.

Cell lysates and conditioned media can be analyzed.

2 samples

[17], [18]

NBS

Non-gel based

¹²C-NBS (light)

¹³C-NBS (heavy)

Labeled to tryptophan indole group

Simple MS spectra can be obtained because there is less tryptophan in protein sequences.

2 samples

[19]

iTRAQ

Non-gel based

Isobaric tags (m/z 305, in total)

(m/z, reporter) + (m/z, balancer):

(113) + (192), (114) + (191), (115) + (190), (116) + (189), (117) + (188), (118) + (187), (119) + (186), (121) + (183)

Labeled to lysine amino group

Expression ratio can be used to quantify the signal intensity of reporter peaks.

Many samples can be assayed in one experiment.

2 ~ 8 samples

[20]