Medicine Nobel for discovery of cellular transport system

Ever wondered how a cell transports the molecules it produced to the right place within and out of the cell membrane. The discovery of the very precise cellular transport system won Nobel for Medicine or Physiology. Two Americans Randy Schekman, James Rothman and a German (settled in USA) Thomas Sudhof won £772,000 prize who share among them. Each one found different mechanisms involved in the functioning of the transport system.

Cells produce different molecules namely hormones, enzymes, cytokines, neurotransmitters. These must be delivered in a fast and precise manner. Failure of which may lead to neurological diseases, immunological diseases, and diabetes. Delivery of this cargo takes place in bubble like vesicles surrounded by membranes.

Randy Schekman in 1970s found the genetic basis for the transportation in yeast cells. He found  vesicles piled up in yeast cells with defective transport systems which were due to genetic mutation. Then he went to find three genes that affect the functioning of the transport system.

James Rothman found the exact protein machinery mechanism that enables vesicles to dock and fuse with their target membranes in mammals. Proteins on the vesicles and target membranes bind to each other and transfer of cargo takes place. There may be number of proteins but the bond takes place only when protein on the vesicle and protein of the membrane are same. The proteins which were found by Rothman and the protein composition of the genes identified by Schekman appeared to be same. This led to the conclusion that the transportation system is as old as evolution itself as it is the same mechanism working in yeast and mammals.

Thomas Sudhof found out how the cargo is delivered with timing and precision and follows a general principle whether in yeast or man. He found out that calcium ions were involved in the controlled release of the vesicles in a precise manner in the nerve cells of brain. He searched for calcium sensitive proteins in the nerve cells and identified molecular machinery that responds to an influx of calcium ions and directs neighbor proteins to bind vesicles to the outer membrane of the nerve cell.