Electron microscopy and image analysis of the multicatalytic proteinase.
One electron micrographs, negatively stained multicatalytic proteinase molecules are viewed end-on (ring shaped) or side-on (rectangular shaped). For aurothioglucose, ammonium molybdate- and phosphotungstate-stained molecules, the dimensions measured are consistent. In contrast, uranyl acetate-staining reveals ring-shaped particles which vary in diameter between 12 and 16 nm. This is due to a partial collapse and substantial flattening of the structure. Digital image analysis of side-on views of the particles reveals a tripartite, reel-shaped structure. Within the ring-like, end-on projections of ammonium molybdate-stained molecules six local centres of mass can be discerned; their position appears to depart, however, from a true six-fold symmetry.
Baumeister
W
W
Max-Planck-Institut für Biochemie, Martinsried, FRG.
Dahlmann
B
B
Hegerl
R
R
Kopp
F
F
Kuehn
L
L
Pfeifer
G
G
D000818:Animals; D003546:Cysteine Endopeptidases / Q000302:isolation & purification; D008854:Microscopy, Electron; D009097:Multienzyme Complexes / Q000302:isolation & purification; D009132:Muscles / Q000201:enzymology; D046988:Proteasome Endopeptidase Complex; D051381:Rats; D013194:Staining and Labeling
D009097:Multienzyme Complexes; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex