Protein Degradation

Biting in the Middle

Science's STKE  21 Jan 2003:
Vol. 2003, Issue 166, pp. tw37-TW37
DOI: 10.1126/stke.2003.166.tw37

The proteasome is a cylindrical molecular machine that promotes the proteolysis of a wide variety of cellular substrates, including many important signaling mediators and regulators. Its architecture is well understood at the molecular level, and it has been assumed that substrates are threaded into the cylinder from their termini for cleavage. Liu et al. have found that, in vitro, the proteasome can cleave internal sites within a protein and can even cleave circular substrates.

C.-W. Liu, M. J. Corboy, G. N. DeMartino, P. J. Thomas, Endoproteolytic activity of the proteasome. Science 299, 408-411 (2003). [Abstract] [Full Text]