Question

What type of information can be gained from an SDS-PAGE?

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Answer 1

An SDS-PAGE is a type of denaturing agarose gel electrophoresis routinely used for resolution of proteins in a sample. The principle of SDS-PAGE lies upon differential unidirectional and linear movement of various proteins in a sample based upon their molecular mass when all the proteins have been given equal negative charge. Following information can be deduced from a standard SDS-PAGE:

1. The pattern of total proteins: Upon running an SDS PAGE, a total profile of cellular proteins can be identified in the sample. This helps in analysing the nature of proteins present such as low molecular weight, high molecular weight and medium molecular weight proteins in a sample.
2. The isoforms of a protein: Using a high-agarose content gel (i.e. 12.5-15%), it is possible to resolve two or more isoforms of a native protein in a single gel. For example, ERK1/2 has two isoforms each weighing 42 and 44 kilo Dalton. These protein isoforms can be very easily and finely resolved using a 12.5% SDS PAGE.
3. Antigen probing: Using the fact that specific proteins can be identified on an SDS PAGE, these specific proteins can be probed using specific antibodies after transferring them onto a solid substratum such as nylon, polyvinylidine fluoride or nitrocellulose membrane. This is a very common, easy, robust and specific application of SDS PAGE and is called western blotting.

Thus, a variety of information can be deduced from SDS PAGE depending upon the need of the experiment.