Discovery of G-proteins and the role of these proteins in signal transduction in cells
Martin Rodbell and Alfred G. Gilman were awarded the Nobel Prize in Physiology or Medicine in 1994 for their discovery of G-proteins, which are vital for passing on signals to the inside of cells from the outside.
To study this phenomenon, the researchers needed individual cells that they could study. Rodbell developed a technique for isolating rat cells from fat tissue and showed that they were still functioning cells by testing their response to insulin. This was the first time that anyone had seen an insulin response in anything less than intact tissue.
With these isolated cells Rodbell was able to find the proteins responsible for signal transduction, G-proteins. As Gilman had posited previously, the cell membrane consists of a receptor (that detects external signals), a transducer (the newly-discovered G-proteins that pass through the membrane) and an amplifier (that passes the message to the inside of the cell).
Without the G-proteins, the signals could not be transmitted. The ‘G’ in G-protein stands for GTP, a nucleotide that provides the energy for the G-proteins to function.
Malfunctioning G-proteins are now known to feature in range of diseases, particularly cholera which directly attacks G-proteins and causes a loss of salt and water.