Word: proteins
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...with a form of early onset colon cancer known to afflict particular families. These genes are carried by as many as 1 in every 200 Americans, making them the most common cause of cancer susceptibility yet discovered. In their normal form, these biological versions of computerized spelling checkers produce proteins that scoot along strands of replicating DNA, searching for tiny typos. When a protein finds an error in one of the words spelled out by DNA's four-letter chemical alphabet, it flashes an alarm. A person born with only one good copy of any of these genes is fine...
...blunderbusses but leave highly individualized fingerprints in the DNA they touch. At the National Cancer Institute, Dr. Curtis Harris, a molecular epidemiologist, has been examining cells from liver- and lung-cancer patients, searching for mutations in a tumor-suppressor gene known as p53 (p stands for the protein the gene makes and 53 for the protein's molecular weight). Smokers who develop lung cancer, Harris has found, show tiny alterations in the p53 gene that differ from those in nonsmokers. They also vary from the changes found in Chinese liver-cancer patients. In the latter group, aflatoxin, a fungal contaminant...
...such a small mistake -- the equivalent of changing the spelling of Smith to Smyth -- have such an impact? Each three-letter "word" of a gene "sentence" spells out the instructions for producing 1 of 20 amino acids, compounds that in turn link to form proteins. A change in just one letter can result in the substitution of one amino acid for another. The new amino acid will be larger, smaller, stiffer or more elastic than the correct one. In ways radical and subtle, it will affect the shape of the protein and its activity. For if a cell is like...
What triggers blood-vessel formation, or angiogenesis, as the process is known? A major factor, scientists believe, is a sudden drop in the cancer cell's production of thrombospondin, a protein that inhibits the growth of new blood vessels. In the normal adult, angiogenesis is not only a rare event, but one cells strive to prevent, save for special circumstances like wound healing. For blood vessels invading joints can cause arthritis, and those invading the retina of the eye can cause blindness. To prevent such damage, cells keep blood vessels at bay by pumping out thrombospondin. At a recent scientific...
...master "on" switch positioned deep in the nucleus. Not surprisingly, many oncogenes, including one called ras, the first human cancer gene ever identified, are involved in this type of signaling pathway. But there are other molecules that determine whether the cell should heed these signals. And the small protein produced by MTS1 appears to be among the most important inhibitors of cell division. Last year researchers at New York's Cold Spring Harbor Laboratory discovered that a protein they called p16 stifled an enzyme that is a growth promoter. Last week it became clear that p16 and the MTS1 protein...