George Emil Palade Biography

George Palade entered the science of cell biology at a time when techniques such as electron microscopy and sedimentation of discrete bits of cell structure were beginning to reveal the minute structure of the cell. He not only advanced these techniques, but also, by investigating the ultrastructure or fine structure of animal cells, identified and described the function of mitochondria as the powerhouse of the cell and of ribosomes as the site of protein manufacture. For his research in the function and structure of such cell components, he shared the 1974 Nobel Prize in physiology or medicine with two other cell researchers, Albert Claude and Christian R. Duvé.

George Emil Palade was born on November 19, 1912, in Jassy, in northeastern Romania. One of three children, Palade came from a professional family--his father, Emil, was a philosophy professor at the University of Jassy, while his mother, Constanta Cantemir, taught elementary school. Palade's two sisters, Adriana and Constanta, would grow up to be a professor of history and a pediatrician, respectively.

Attending school in Buzau, Palade entered the University of Bucharest in 1930 as a medical student. Ten years later he received his degree, having completed his internship as well as a thesis on the microanatomy of the porpoise kidney. Having earned his medical degree, Palade chose to focus on research instead of practicing medicine. His particular interest was histology, or the microscopic structure of plant and animal tissue. With the advent of the World War II, Palade was drafted into the army and stationed at the University of Bucharest Medical School as an assistant professor of anatomy. In 1941, he married and he and his wife eventually had two children.

In 1945, after being discharged from the army, Palade obtained a research position at New York University. While there, he met the eminent cell biologist Albert Claude, who had pioneered both the use of the electron microscope in cell study and techniques of cell fractionation (the separation of the constituent parts of cells by centrifugal action). The older scientist invited Palade to join the staff at the Rockefeller Institute (now Rockefeller University), and in 1946 Palade accepted a two-year fellowship as visiting investigator. In 1947, the communist-led government in Romania declared the country a people's republic and forced the abdication of King Michael. Palade, who had always planned to return home to work, now opted to remain in the United States. He became a U.S. citizen in 1952 and a full professor of cytology at Rockefeller in 1958.

At the Rockefeller Institute, Palade's first achievements came in the preparation of cell tissue for both the fractionation process and electron microscopy. In the former, collaborating with W. C. Schneider and George Hogeboom, Palade introduced as a fixative the use of gradient sucrose, and in the latter, buffered osmium tetroxide. However, his accomplishments soon went beyond improvements in methodology. Claude left the institute in 1949, and in the next decade Palade and his collaborators, building on Claude's work, reported groundbreaking descriptions of the fine appearance of the cell and of its biochemical function. Concentrating on the cytoplasm--the living material in the cell outside the nucleus--Palade was first attracted to larger organelles (bodies of definite structure and function in the cytoplasm) which Claude had earlier called "secretory granules." Palade showed that these tiny sausage-shaped structures, mitochondria, are the site where biochemical energy for the cell is generated. Animal cells typically contain a thousand such mitochondria, each creating adenosine triphosphate--ATP, a high-energy phosphate molecule--through enzymic (enzyme-catalyzed) oxidation or breakdown of fat and sugar. The ATP is then released into the cytoplasm where it powers energy-requiring mechanisms such as nerve impulse conduction, muscle contraction, or protein synthesis.

Using the high-power electron microscope (a device that utilizes electrons instead of light to form images of minute objects), Palade next revealed a delicate tracery, subsequently termed the endoplasmic reticulum by his collaborator, Keith R. Porter. The endoplasmic reticulum is a series of double-layered membranes present throughout all cells except mature erythrocytes, or red blood cells. Its function is the formation and transport of fats and proteins. By far Palade's most significant work was with so-called microsomes, small bodies in the cytoplasm that Claude had earlier identified and shown to have a relatively high ribonucleic acid (RNA) content. RNA is the genetic messenger in protein synthesis. Palade observed these microsomes both as free bodies within the cytoplasm, and attached to the endoplasmic reticulum. In 1956, using a high-speed centrifuge, Palade and his colleague Philip Siekevitz were able to isolate microsomes and observe them under the electron microscope. They discovered that these microsomes were made of equal parts of RNA and protein.

Palade assumed that these RNA-rich microsomes were in fact the factories producing protein to sustain not only the cell but also the entire organism. The microsome was renamed the ribosome, and Palade and his team went to work to investigate the pathway of protein synthesis in the cell. Palade and Siekevitz began a series of experiments on ribosomes of the liver and pancreas, employing autoradiographic tracing, a sophisticated process similar to X-ray photography in which a picture is produced by radiation. Investigating in particular exocrine cells (those that secrete externally) of the guinea pig pancreas, the team was able, by 1960, to show that ribosomes do in fact synthesize proteins that are then transported through the endoplasmic reticulum. Further research with Lucien Caro, J. D. Jamieson, C. Redman, David Sabatini, and Y. Tashiro elucidated the function of the larger ribosomes attached to the endoplasmic reticulum, establishing them as the site where amino acids assemble into polypeptides (chains of amino acids). Palade's team also traced the transportation network as well as the function of the Golgi complex, tubelike structures where proteins are sorted before final transport to the cell surface for export.

Having completed his work on protein synthesis, Palade turned his attention to cellular transport--the means by which substances move through cell membranes. Working with Marilyn G. Farquhar, Palade demonstrated by electron micrography (images formed using an electron microscope) that molecules and ions were engorged by sacs or vesicles that move to the surface from within the cell. These vesicles actually merge with the outer membrane for a time, and then swallow up and bring the substances inside the cell. This vesicular model was in distinct contrast to the then current pore model whereby it was thought that molecules simply entered the cell through pores in the membrane.

Following the death of his wife in 1969, Palade remarried. In 1972, he left the Rockefeller Institute and became a full professor of cell biology at Yale University, continuing his research in cell morphology and function, but also turning to practical clinical uses of his discoveries. His later work is an attempt to establish links between defects in cellular protein production and various illnesses. In 1974, Palade shared the Nobel Prize in Physiology or Medicine with his former mentor, Albert Claude, and with Christian R. de Duvé, for their descriptions of the detailed microscopic structure and functions of the cell. He was also the recipient of the Passano Award in 1964, the Albert Lasker Basic Medical Research Award in 1966, the Gairdner Foundation Special Award in 1967, and the Horowitz Prize in 1970. In addition, Palade is the founding editor of the Journal of Cell Biology.

In 1990, Palade left Yale to become the dean for scientific affairs and to serve as a professor-in-residence in cellular and molecular medicine at the University of California, San Diego.