A giant protease with a twist: the TPP II complex from Drosophila studied by electron microscopy |
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Authors: | Rockel Beate Peters Jürgen Kühlmorgen Brigitte Glaeser Robert M Baumeister Wolfgang |
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Institution: | Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA. |
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Abstract: | Tripeptidyl peptidase II (TPP II) is an exopeptidase of the subtilisin type of serine proteases that is thought to act downstream of the proteasome in the ubiquitin-proteasome pathway. Recently, a key role in a pathway parallel to the ubiquitin-proteasome pathway has been ascribed to TPP II, which forms a giant protease complex in mammalian cells. Here, we report the 900-fold purification of TPP II from Drosophila eggs and demonstrate via cryo-electron microscopy that TPP II from Drosophila melanogaster also forms a giant protease complex. The presented three-dimensional reconstruction of the 57 x 27 nm TPP II complex at 3.3 nm resolution reveals that the 150 kDa subunits form a superstructure composed of two segmented and twisted strands. Each strand is 12.5 nm in width and composed of 11 segments that enclose a central channel. |
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