| By
Robert Krulwich
ABC News
Genes
don't actually do anything themselves. They hold instructions for making proteins,
and it's the proteins that actually perform functions in our bodies.
"When
you look at yourself in a mirror, you're looking mostly at protein. The outer
layer of your body is made of protein Ñ keratin Ñ your hair is made of keratin,
your cornea is made of protein," says William Haseltine, chairman of Human Genome
Sciences, one of the private companies that has been decoding the genome. "Proteins
are the essence of life."
We're Like a Fruitfly?
Preliminary
findings from the government-led Human Genome Project estimate that human beings
have 30,000-40,000 genes Ñ only twice as many as the humble fruitfly. (Haseltine's
group believes that humans have more genes, as many as 120,000.)
"That's
really bothersome to many people," says Eric Lander, director of the Whitehead
Institute's Center for Genome Research at the Massachusetts Institute of Technology,
part of the Human Genome Project. "Because we really like to think of ourselves
as a lot more than twice as complex."
But humans are far more complex than
fruitflies. Genetic scientists suspect that is because our genes are better at
making proteins than the genes in a fruitfly.
A gene that appears identical
in both creatures might produce one or two proteins in a fruitfly, but four in
a human being. And in a human those four proteins could combine and interact to
make bigger and more proteins.
"So when you might only have say 30,000
genes, you could have 100,000 distinct proteins, and when you're done putting
all the different modifications on them, there might be a million of them," says
Lander.
Lander and his colleagues are investigating how and why human
genes produce more proteins than other creatures' genes. "This is just the beginning
of a very comprehensive, systematic program to understand all the components and
how they connect with each other," he says.
Proteomics Ñ the study of
the proteome Ñ promises to be the next big thing. Understanding proteins could
lead to new advances in medicine and, theoretically, ways to enhance the bodies
we are born with.
New protein businesses and protein maps and libraries
are being started all over the world, and Wall Street is very interested.
Fixing
Sick Proteins
Proteins can be visualized as tangles of ribbons, each
with a specific shape that defines its identity and function. Diseases can distort
a protein's shape, impairing its function by making it unrecognizable to other
proteins programmed to interact with it.
Healthy Protein. This is a visualization
of a healthy protein that you can find in humans' lung cells. The protein's function
is to move salt in and out of the lung cells. Every hook, every fold is locked
in place, so other proteins can work with it to regulate salt levels. (The loops
and folds in this illustration are hypothetical; scientists have not yet identified
the protein's actual shape.)
Misshapen Protein. This is the same protein
affected by cystic fibrosis. The disease causes genes to produce misshapen proteins
in the lung cells Ñ in this illustration distorting the loop at lower left. Because
it has the wrong shape, it is ignored or destroyed by other proteins, so it can't
do its job. Salt builds up in the lung cells, producing thick mucus that can become
infected and kill the patient.
Fixing the Protein. At some point in the
future, drug companies may be able to create proteins to fix the misshapen protein.
The repair protein, at left, would twist the loop back into place, restoring the
misshapen protein to its healthy form. Salt would be regulated in the patient's
lungs, and they would no longer be in danger from mucus build-up.
Some
companies are conducting preliminary trials on protein-fixing medicines, but it's
unclear whether the drugs will work, or how long it might take to learn more about
proteins.
"It's always risky to predict timetables," warns Collins.
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