Several thousand different proteins are expressed at any one time in a particular sample tissue or organism; 2-D gel electrophoresis makes it possible to resolve these proteins. Scientists may compare samples from normal and diseased tissues, or from tissue samples harvested over the course of development, to identify those proteins whose expression levels change. With the 2-D method it is even possible to distinguish functionally distinct proteins encoded by the same gene, such as mRNA splice variants and proteins bearing post-translational modifications (e.g., methylation, glycosylation, and phosphorylation).
Two-dimensional gel technology was first described more than 25 years ago by Patrick O'Farrell.3 However, recent advances have made the technique more popular, by improving what was often a harrowing and time-consuming experience. Fragile polyacrylamide tube gels containing drift-prone carrier ampholytes are now replaced by immobilized pH gradient (IPG) strips that allow for simultaneous "in-gel" rehydration and sample application, offer mechanical stability due ...
