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About SickKids

October 7, 2013

SickKids scientists’ discovery makes common gel electrophoresis test more reliable

By Erin Collett

The Hospital for Sick Children (SickKids) scientists have made a breakthrough in understanding why membrane proteins behave unusually on SDS-PAGE, one of the most commonly-used biochemical lab methods.

The study, directed by Dr. Charles Deber, a Senior Scientist in the Molecular Structure & Function Program at SickKids Research Institute, is published in the September 24 issue of Proceedings of the National Academy of Sciences (PNAS).

Proteins are among the most important building blocks of life. They form the structure of hair, skin, and muscle, carry oxygen in the blood, act as the pumps and channels that take nutrients into the body, and allow the body’s cells and organs to “talk” to one another.

Membrane proteins comprise nearly one third of all genes in humans and are acted upon by more than 50 per cent of current drugs. When the membrane proteins are absent or dysfunctional, paediatric diseases such as cystic fibrosis, diabetes, and certain cancers can result.

SDS-PAGE analysis involves taking proteins and encasing them in soap-like detergents. They are then placed on a gel plate, where they move from the top toward the bottom. Generally, the smaller proteins move faster and bigger proteins mover slower. Where the proteins end up on the plate determines their size.

However, this technique did not always produce the right answer when used with membrane proteins. Since scientists have been at a loss to explain why, researchers had to spend extra time analyzing their results.

Deber, along with lead author Dr. Arianna Rath and co-author Dr. Fiona Cunningham, found that this unusual behaviour can be directly attributed to the acrylamide concentration in the gel. Their PNAS paper includes a reference chart that researchers can now use to obtain the correct membrane protein sizes, thereby helping to make all SDS-PAGE experiments straightforward and more reliable.