Cell Membrane Transport Proteins Identified

Researchers have identified some of the proteins comprising the clathrin-coated vesicles (CCVs) that are responsible for transporting nutrients and other molecules through the cell membrane.

Clathrin is a protein composed of three heavy chains (180 kD) and three light chains (34 and 36 kD), which form a basketwork of triskelions (figures consisting of three bent lines) radiating from a center around a coated vesicle. Investigators at McGill University (Montreal, Canada) prepared preparations of 80-90% pure CCVs from extracts of rat brains and livers using subcellular fractionation with analysis by electron microscopy.


They reported in the March 8, 2004, online edition of the Proceedings of the [U.S.] National Academy of Sciences that they had identified 209 proteins associated with clathrin-coated vesicles. About half of the proteins were already known to be associated with clathrin-coated vesicles, while the rest were novel proteins or proteins with known function that were not previously known to be involved in this process.

"Proteins are the workhorses in our cells,” explained senior author Dr. Peter McPherson, associate professor of neurology at McGill University. "Increasingly, we are learning that proteins do not work in isolation, but function in large arrays that form protein machines. Proteomics is exciting because it allows us to breakdown this complex machine into its component parts. We can then figure out how it is assembled, how the proteins interact with one another, and what goes wrong in disease.”



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