To determine which among the 6,000 yeast proteins interact with each other, Maslov and Sneppen collected data on protein interactions in yeast cells from a public database. They then compared the resulting network of interactions to a simulated pattern -- produced by a computer-modeling program -- in which proteins interact randomly.
"If you took a given number of proteins and distributed interactions among them randomly, you would hardly find any particular protein that would have a lot of interactions. Proteins would all 'talk' randomly with each other in such a network," Maslov says. "So, hubs of highly-interacting proteins are not something that you would expect to happen by pure chance."
But the scientists did observe hubs of interacting proteins in the yeast cells. The connections between hub proteins reveal an "emergent property" that acts beyond the level of the functions of the individual proteins and makes them act together to coordinate their functions. Studying these interactions can help identify these coordinated functions, and may also reveal intrinsic features of the interacting proteins.
The "holistic" approach taken by Maslov is part of an ongoing interdisciplinary effort in which scientists are trying to understand phenomena involving many proteins, such as diseases. The understanding of how protein interaction networks are designed might, for instance, help scientists better understand the causes of cancer. One of the hubs in the human protein network, called p53, has a major role in preventing cells from developing into a tumor.
"The computer modeling program developed in this work can be applied to interactions in other networks such as food webs in ecosystems, neural networks, the Internet, and even among stock market agents," Maslov says.
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Contact: Karen McNulty Walsh
kmcnulty@bnl.gov
631-344-8350
DOE/Brookhaven National Laboratory
2-May-2002