title: A giant protease with a twist: the TPP II complex from Drosophila studied by electron microscopy.
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.
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA.
authors.forename: Beate
authors.initials: B
authors.lastname: Rockel
authors.forename: Jürgen
authors.initials: J
authors.lastname: Peters
authors.forename: Brigitte
authors.initials: B
authors.lastname: Kühlmorgen
authors.forename: Robert M
authors.initials: RM
authors.lastname: Glaeser
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumeister
mesh_terms: D000626:Aminopeptidases; D000818:Animals; D020285:Cryoelectron Microscopy; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D029721:Drosophila Proteins / Q000737:chemistry / Q000648:ultrastructure*; D004527:Egg Proteins / Q000737:chemistry / Q000648:ultrastructure; D007091:Image Processing, Computer-Assisted; D046911:Macromolecular Substances; D008958:Models, Molecular; D011487:Protein Conformation; D012697:Serine Endopeptidases / Q000737:chemistry / Q000648:ultrastructure*
chemical_list: D029721:Drosophila Proteins; D004527:Egg Proteins; D046911:Macromolecular Substances; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C048001:tripeptidyl-peptidase 2; D012697:Serine Endopeptidases