Research NewsCell Biology

Cells Count Proteins to Keep Their Telomeres in Line

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Science  14 Feb 1997:
Vol. 275, Issue 5302, pp. 928
DOI: 10.1126/science.275.5302.928

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Cells that divide repeatedly, such as cancer cells, germ-line cells, and microorganisms such as yeast, have to take good care of their telomeres, the specialized stretches of repetitive DNA at the ends of their chromosomes. Because of a quirk in the enzymes that replicate the DNA, the chromosomes shorten a little with each cell division, and for cells to keep dividing they have to add back the telomere DNA. Otherwise, essential genes could be lost. New results appearing on pages 973 and 986 now show that one way yeast cells keep track of how long their telomeres are is by counting the copies of a protein called Rap1 bound to the telomere DNA.