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Science 327 (5968): 966-967

Copyright © 2010 by the American Association for the Advancement of Science

Cell Biology

When the Beginning Marks the End

Axel Mogk, and Bernd Bukau

Acetylation of the amino terminus (Nt-acteylation) of a protein is one of the most common modifications, occurring in about 50% of yeast proteins and more than 80% of human proteins (1). It is catalyzed by N-terminal acetyltransferases, occurs predominantly on a nascent polypeptide chain as it is synthesized, and seems to be irreversible. So far, the biological role of Nt-acetylation has been enigmatic; only in a few cases has it been reported to affect protein functionality [for instance, nonacetylated actin is less efficient at assembling microfilaments (2)]. Controlling the activity of individual proteins cannot, however, explain the massive Nt-acetylation of bulk proteins. On page 973 in this issue, Hwang et al. (3) demonstrate that acetylation of the amino terminus of a protein can function as a degration signal (degron), revealing an entirely unexpected role of acetylation in protein turnover and possibly homeostasis.

Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg 69120, Germany.

E-mail: bukau{at}

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