BBC News Online science editor
Biologists have produced a detailed map of protein
interactions in a complex organism - the fruit fly.
A fruit fly and its protein interaction
which are made by genes, are the building blocks of tissues
as well as the basis for molecular interactions that enable
an organism to live.
The protein interaction map will allow a new insight into a
highly complex metabolic system, similar in many ways to the
The research is to be published in a future issue of the journal
'A starting point'
Scientists, from the US biotech company CuraGen in association
with several US Universities, have produced a draft map of 20,405
interactions between 7,048 proteins in the fruit fly.
This map is a starting point for what is being called a systems
biology modelling of animals including humans, say the researchers
in their report.
For decades the fruit fly has been opening the door to a better
understanding of genetics. Its small genetic blueprint or genome,
small size and short lifespan has made it an invaluable aid
to study how genes work.
It also has many of its genes in common with humans and so
has provided a way to study human diseases.
Now this lowly organism is showing the direction research is taking
after the human genome has been decoded.
PROTEIN INTERACTION MAP
A molecular snapshot of the protein interactions
within a fruit fly cell.
Dance of proteins
An organism's genome is a two-dimensional and static description
of a living creature. To come to life it must be translated
into action, rather like a screenplay must be turned into acting.
Genes in the nucleus of a cell act as templates to produce
proteins, which move out into the cell to perform a specific
task, or to get together with other proteins to make a larger
Many proteins interact with others, for example, to liberate
the energy a cell requires to function.
In its complexity and simplicity, life is a dance of proteins.
There is the genome - the master genetic blueprint - that resides
in the cell nucleus. It interacts with ribosomes - which turn
the DNA code into proteins.
Some proteins then interact with a structure called the Golgi
complex, which inspects packages and labels proteins before handing
them over for distribution elsewhere in the cell.
A protein called tubulin forms a molecular scaffold along which
proteins can be transported around the cell. Some go to the
cell's outer membrane and are ejected.
Knowledge of how proteins behave and interact is essential
for any understanding of life itself.
So, having completed the decoding an organism's genome, scientists
now want to make a protein map - its proteome.
'A real tour de force'
The new protein interaction map means that the fruit fly's
proteome is probably the best studied to date.
"The Science publication is a real tour de force in systems
biology," says Richard Lifton of CuraGen and the Yale University
School of Medicine.
Dr John Chant of CuraGen told BBC News Online: "When I look
at the new map I can see how complicated it is. But as well
as that there is a beauty to it. The map undoubtedly contains
a massive amount of information."
"The vast amount of important new information reported in this
paper will provide researchers around the globe with productive
avenues to pursue for years to come," says Richard Lifton.
"Much of our understanding of the complex biochemical pathways
that underlie human disease has been derived from the study
of the fruit fly, and having the opportunity to integrate this
huge proteomic dataset with prior knowledge of this well-studied
organism will be a boon to the understanding of normal biology,
as well as human disease," he adds.
To make the map scientists cloned all the fruit fly's genes
and developed a way to take a molecular 'snapshot' of what was
going on inside the organism. They say they have obtained data
about "a significant fraction of the organism's protein-protein
"We have had biologists, bioinformation scientists and computer
scientists working together very closely over this," Dr John
Chant told BBC News Online.
They tracked more than 20,000 interactions involving approximately
7,000 genes. Mathematical modelling of the interactions between
apparently disconnected proteins revealed a hidden level of
organisation between genes.
The beginnings of a new order are being glimpsed with local
activity that links multiprotein complexes as well as 'global'
interconnections among and within various protein complexes.
The map will have direct relevance to humans. "Given the proven
utility of Drosophila (fruit flies) as a model system, many
of the linkages uncovered in this report should be examined
for their conservation in human cells," the researchers say.