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This figure shows the capsid or outer shell of a virus
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This figure shows the capsid, or outer shell, of a virus called bacteriophage T4.

June 8, 2010
This figure shows the capsid, or outer shell, of a virus called bacteriophage T4. Proteins called gp23 are represented in blue and gp24 are represented in magenta. Both of these proteins are critical for the assembly of the T4 capsid. Researchers have found that the T4 virus and another virus called HK97 both have similar "protein folds" in their outer shells. These findings are providing further evidence that the protein envelope protecting DNA in viruses evolved billions of years ago from a common ancestor and uses the same basic protein fold to construct the outer shell. The researchers used x-ray crystallography to view the gp24 protein at a resolution of 2.9 angstroms and electron microscopy to view the virus capsid at 22-angstrom resolution. An angstrom is one ten-billionth of a meter, or roughly one-millionth as wide as a human hair.

This is generally NSF funded research, and is aimed at understanding the structures of viruses. Many people were involved in this research in different capacities, including Marc C. Morais, Kyung H. Choi, Joya S. Koti, Paul R. Chipman, Dwight L. Anderson and Michael G. Rossmann. [One of three related images. See Next Image.] (Date of Image: May 18, 2005)


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