The content you've requested is available without charge only to active Sigma Xi members and
If you are an active member or an individual subscriber, please log in now in order to access this article.
If you are not a member or individual subscriber, you can:
Hemoglobin—the oxygen-transport protein that gives blood its red color—got its start at about the time life originated on earth, nearly four billion years ago. Now it is almost ubiquitous, appearing in the cells of plants, animals and even bacteria, and a study of this protein affords scientists a rare glimpse back as well as forward in time. A look at the ancestral hemoglobins indicates that newly arising proteins co-opt the chemistry of older ones and gain new functions through structural alterations. But these studies have revealed an additional way to modify function. Scientists are coming to the realization that changes in a protein's regulation—the when and how of its expression—can also give rise to functional differences. The surprise, says the author, is that these regulatory changes outpace structural ones—an important lesson for students of molecular evolution and a possible indicator of where protein evolution will go in the future.
Connect With Us:
An early peek at each new issue, with descriptions of feature articles, columns, and more. Every other issue contains links to everything in the latest issue's table of contents.
News of book reviews published in
and around the web, as well as other noteworthy happenings in the world of science books.
To sign up for automatic emails of the
American Scientist Update
issues, create an
, then sign up in the
My AmSci area
JSTOR, the online academic archive, contains complete back issues of American Scientist from 1913 (known then as the Sigma Xi Quarterly) through 2005.
The table of contents for each issue is freely available to all users; those with institutional access can read each complete issue.
View the full collection here.
Receive notification when new content is posted from the entire website, or choose from the customized feeds available.