Study of proteins offers insights into organization of biologica...( the network's disintegration than the r...)

In their Nature study, Vidal and his colleagues sought to understand why hub proteins play such a seemingly central role in cell life. By entering into a computer all that is known about the interactions among yeast-cell proteins, the investigators were able to make a digital simulation of the protein network. They selectively removed hub and non-hub proteins and measured how this affected the overall number of connections between proteins. They found that while eliminating non-hubs had very little effect on the amount of connections, eliminating hubs caused connection length to increase. "The extent of disruption caused by removal of hubs is clearly greater than that caused by removal of non-hubs," Vidal remarks. "It's as though one closed a main road in a city, forcing traffic to follow a lengthy detour to reach its destination."

Analyzing data generated by gene-chip technology, investigators found that some hubs are active at the same time as their partners like bulbs in a flashing sign while others are active at different times like bulbs blinking on a Christmas tree. They dubbed the first group "party" hubs and the second group "date" hubs.

When party hubs were taken out of the mix, there was very little effect on the number of protein connections within the cell. When date hubs were removed, however, connection length rose sharply, meaning it take more "hops" to move between nodes.

Researchers concluded that party hubs work primarily within "modules" that perform specific biological functions, whereas date hubs connect modules to one another. The researchers suggest that a similar structure could be found in many other man-made and natural networks.

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Contact: Janet Haley
janet_haley@dfci.harvard.edu
617-623-5665
Dana-Farber Cancer Institute
9-Jun-2004