Sep. 19, 2010 The number of times our cells can divide is
dictated by telomeres, stretches of DNA at the tips of our
chromosomes. Understanding how telomeres keep our chromosomes --
and by extension, our genomes -- intact is an area of intense
scientific focus in the fields of both aging and cancer. Now,
scientists at The Wistar Institute have published the first
detailed report on the structure and function of a crucial
domain in the protein known as Cdc13, which sustains telomeres
by clamping to DNA and recruiting replicating enzymes to the
area. While the nature of this portion of Cdc13 had previously
eluded scientists, the Wistar researchers found that two copies
of the protein bind together to form what is called a "dimer,"
and how that dimer physically interacts with DNA, regulating how
enzymes called telomerases access and lengthen the telomeres.
The study was performed using the yeast gene, however, this
essential life process has changed little through evolution, and
evidence suggests that the human