For the past 24 years, high-resolution two-dimensional
polyacrylamide gel electrophoresis (2-D PAGE) has been
the technique of choice for analyzing the protein composition
of cells, tissues, and fluids, as well as for studying
changes in global patterns of gene expression elicited
by a wide array of effectors. The technique, which was
originally described independently by O'Farrell and
Klose, offers the highest resolution of protein separation
and, therefore, plays a central role in “proteomics,”
an area of functional genomics that combines a plethora
of techniques to resolve (2-D PAGE), identify (peptide
sequencing by Edman degradation, mass spectrometry, Western
immunoblotting), quantify (scanners, phosphorimagers),
and characterize proteins, as well as to store (image analysis
and 2-D PAGE databases), communicate, and interface protein
data with that emerging from the various genome mapping
and sequencing projects. Proteomics, together with genomics,
cDNA arrays, phage antibody libraries, and transgenics
and knockouts, today provide an impressive array of technologies
for studying gene expression in both health and disease.