Same gene, different results
Scientists are learning to their surprise that a single gene very often functions differently in different parts of the body.
Genes generally work by producing some molecule that serves a given function in the body. However, scientists have long known one gene can produce slightly different forms of the same molecule, by skipping or including certain alternative bits of genetic code.
The new research indicates this phenomenon, known as alternative splicing, is far more prevalent and varies more between tissues than previously believed. Nearly all human genes, about 94 percent, generate more than one form of their products, researchers reports in the Nov. 2 online edition of the research journal Nature.
“A decade ago, alternative splicing of a gene was considered unusual, exotic… it turns out that’s not true at all,” said Christopher Burge, senior author of the paper and a biologist at the Massachusetts Institute of Technology.
Human genes typically contain several “exons,” or DNA sequences that code for amino acids, the building blocks of large molecules called proteins. A single gene can produce multiple sequences of amino acids, depending on which exons are included in the instructions that travel from the gene to a cell’s protein-building machinery.
Two different forms of the same protein, known as isoforms, can have different, even opposite functions. For example, one protein may set in motion chains of events that lead cells to commit suicide when necessary. A close relative of the same protein may instead promote longer cell survival.
Source: http://www.world-science.net/othernews/081102_genes
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