Keeping the lid on destruction

Proteins slated for destruction enter the proteasome core particle (CP) through a channel that usually remains closed for safety's sake. It opens when a CP associates with the proteasome regulatory particle (RP), which recognizes the substrates and ushers them into the channel. What persuades the channel to open? A ring of six ATPases straddles the channel, and those enzymes have been thought to figure in this process. Now, Alwin Köhler and his colleagues in the laboratories of Daniel Finley and Alfred Goldberg (Harvard Medical School, Boston, MA) report, surprisingly, that just one of the six ATPases, Rpt2, is the key that unlocks the channel. In addition, the products of protein degradation exit the proteasome the same way that they came in, pointing to some possible traffic problems.

The paper also reports on...