The Power of DNA Sequence Comparison
After a new gene is found, biologists usually have no idea about its function.
A common approach to inferring a newly sequenced gene’s function
is to find similarities with genes of known function. A striking example of
such a biological discovery made through a similarity search happened in
1984 when scientists used a simple computational technique to compare the
newly discovered cancer-causing -sis oncogene with all (at the time) known
genes. To their astonishment, the cancer-causing gene matched a normal
gene involved in growth and development called platelet-derived growth
factor (PDGF).1 After discovering this similarity, scientists became suspicious
that cancer might be caused by a normal growth gene being switched on at
the wrong time—in essence, a good gene doing the right thing at the wrong
time.