| Citation | Distinguished for his studies of the control of protein synthesis in animal cells and for the discovery of cyclin, a protein which regulates the eukaryotic cell cycle. Together with Jackson and their students, he defined steps in formation of the initiation complex in protein synthesis, showing that the 40S ribosomal subunit binds initiator tRNA before it binds mRNA, and that this step was the target of inhibitors such as double-stranded RNA or haem deficiency. They showed that inhibition of protein synthesis is mediated by reversible phosphorylation of initiation factor eIF-2 by two distinct protein kinases and they elucidated the unexpected roles of thioredoxin and thioredoxin reductase in protein synthesis. With Ruderman and Rosenthal, he demonstrated selective translational control of mRNA in early clam embryos. This led to Hunt's discovery of cyclin as a protein which is selectively destroyed in mitosis. He subsequently cloned and sequenced cyclin cDNA from sea urchins and frogs and showed by elegant mRNA ablation experiments that cyclin translation is necessary for mitosis in frog embryos. He has also shown that cyclin is a subunit of the mitosis-promoting factor which regulates entry into mitosis. His discovery and characterization of cyclin are major contributions to our knowledge of cell cycle regulation in eukaryotic cells. |