The irony is that although mutated forms of the ras protein can lead to cancer, organisms cannot survive without ras. So experimental cancer therapies targeted at ras must knock out some of its function, but not all. This balance is what the researchers hope might one day be achieved by blocking Rce1, which reduces but does not eliminate ras function, at least in yeast cells. Determining the enzymatic mechanism of Rce1 will be critical to developing potent inhibitors. Yet this information has been impossible to obtain from in vitro experiments or even from the primary structure of the gene.
Scientists believe there are only four classes of such protease enzymes.
But Rce1 matches none of the known types. The yeast ras protein on which the researchers worked is very similar to the human variety, said Ashby. So the researchers are hopeful their findings will hold true across the two species. They are now looking for the same type of enzyme activity in human cells and hope to have findings soon. It's in yeast, worms, fruit flies, and all mammals, including humans.