Imperial Cancer Research Fund, Clare Hall
South Mimms, UK.
Tim Hunt discovered
cyclins, proteins that bind to the CDK molecules.
Cyclins regulate the CDK activity and select the
target proteins to be phosphorylated. The proteins
were named cyclins because of their cyclic variation
in amount during the cell cycle (figure bottom left).
Hunt's discovery that cyclins were degraded during
mitosis turned out to be another fundamental control
mechanism in the cell cycle.
Tim Hunt discovered the first
cyclin molecule in 1982, using eggs from sea urchin,
Arbacia, as a model system. He also found that
cyclins, like CDK, were conserved during evolution.
Today around ten different cyclins have been found in