Martin Rodbell

(1925 - 1998)

Martin Rodbell was born on December 1, 1925, in Baltimore, Maryland. He entered Johns Hopkins University in 1943, with interests in biology and French existential literature. In 1944, his studies were interrupted by his military service as a U.S. Navy radio operator during World War II. He returned to Hopkins in 1946 and received his B.S. in biology in 1949. Rodbell received his Ph.D. in biochemistry at the University of Washington in 1954. He did post-doctoral work at the University of Illinois at Urbana-Champaign from 1954 to 1956. In 1956, Rodbell accepted a position as a research biochemist at the National Heart Institute, part of the National Institutes of Health, in Bethesda, Maryland.

In 1985, Rodbell became Scientific Director of the NIH's National Institute of Environmental Health Sciences in Chapel Hill, North Carolina where he worked until his retirement in 1994.

He shared the 1994 Nobel Prize in Physiology or Medicine with Alfred G. Gilman for "their discovery of G-proteins and the role of these proteins in signal transduction in cells."

Rodbell died on in Chapel Hill December 7, 1998, of multiple organ failure after an extended illness.

Research

Reflecting the increasingly common analogies between computer science and biology in the 1960s, Rodbell believed that the fundamental information processing systems of both computers and biological organisms were similar. He asserted that individual cells were analogous to cybernetic systems made up of three distinct molecular components: discriminators, transducers, and amplifiers (otherwise known as effectors). The discriminator, or cell receptor, receives information from outside the cell; a cell transducer processes this information across the cell membrane; and the amplifier intensifies these signals to initiate reactions within the cell or to transmit information to other cells.

In December 1969 and early January 1970, Rodbell was working with a laboratory team that studied the effect of the hormone glucagon on a rat liver membrane receptor-the cellular discriminator that receives outside signals. Rodbell discovered that ATP (adenosine triphosphate) could reverse the binding action of glucagon to the cell receptor and thus dissociate the glucagon from the cell altogether. He then noted that traces of GTP (guanosine triphosphate) could reverse the binding process almost one thousand times faster than ATP. Rodbell deduced that GTP was probably the active biological factor in dissociating glucagon from the cell's receptor, and that GTP had been present as an impurity in his earlier experiments with ATP. This GTP, he found, stimulated the activity in the guanine nucleotide protein (later called the G-protein), which, in turn, produced profound metabolic effects in the cell. This activation of the G-protein, Rodbell postulated, was the "second messenger" process that Earl W. Sutherland had theorized. In the language of signal transduction, the G-protein, activated by GTP, was the principal component of the transducer, which was the crucial link between the discriminator and the amplifier. Later, Rodbell postulated, and then provided evidence for, additional G-proteins at the cell receptor that could inhibit and activate transduction, often at the same time. In other words, cellular receptors were sophisticated enough to have several different processes going on simultaneously.

The following press release from the Royal Swedish Academy of Sciences describes Rodbell's work:

It has been known for some time that cells communicate with each other by means of hormones and other signal substances, which are released from glands, nerves and other tissues. It is only recently that we have begun to understand how the cell handles this information from the outside and converts it into relevant action - i.e. how signals are transduced in cells.

The discoveries of the G-proteins by the Americans Alfred G. Gilman and Martin Rodbell have been of paramount importance in this context, and have opened up a new and rapidly expanding area of knowledge.

G-proteins have been so named because they bind guanosine triphosphate (GTP). Gilman and Rodbell found that G-proteins act as signal transducers, which transmit and modulate signals in cells. G-proteins have the ability to activate different cellular amplifier systems. They receive multiple signals from the exterior, integrate them and thus control fundamental life processes in the cells.

Disturbances in the function of G-proteins - too much or too little of them, or genetically determined alterations in their composition - can lead to disease. The dramatic loss of salt and water in cholera is a direct consequence of the action of cholera toxin on G-proteins. Some hereditary endocrine disorders and tumours are other examples. Furthermore, some of the symptoms of common diseases such as diabetes or alcoholism may depend on altered transduction of signals through G-proteins.

Sources: Wikipedia, Nobelprize.org, Picture courtesy of: National Institute of Environmental Health Sciences