Pituitary multicatalytic proteinase complex. Specificity of components and aspects of proteolytic activity

Biochemistry ◽  
1989 ◽  
Vol 28 (24) ◽  
pp. 9270-9278 ◽  
Author(s):  
Marian Orlowski ◽  
Charlene Michaud
Keyword(s):  
Proteolytic Activity ◽  
Multicatalytic Proteinase ◽  
Multicatalytic Proteinase Complex

scholarly journals The multicatalytic proteinase complex (proteasome): structure and conformational changes associated with changes in proteolytic activity

1993 ◽  
Vol 292 (3) ◽  
pp. 857-862 ◽  
Author(s):  
H Djaballah ◽  
A J Rowe ◽  
S E Harding ◽  
A J Rivett
Keyword(s):  
Proteolytic Activity ◽  
Rat Liver ◽  
Conformational Changes ◽  
Rotational Symmetry ◽  
Sedimentation Velocity ◽  
Sodium Thiocyanate ◽  
Cylindrical Shape ◽  
Multicatalytic Proteinase ◽  
Negative Stain ◽  
Multicatalytic Proteinase Complex

The multicatalytic proteinase complex or proteasome is a high-molecular-mass multisubunit proteinase which is found in the nucleus and cytoplasm of eukaryotic cells. Electron microscopy of negatively stained rat liver proteinase preparations suggests that the particle has a hollow cylindrical shape (approximate width 11 nm and height 17 nm using methylamine tungstate as the negative stain) with a pseudo-helical arrangement of subunits rather than the directly stacked arrangement suggested previously. The side-on view has a 2-fold rotational symmetry, while end-on there appears to be six or seven subunits around the ring. This model is very different from that proposed by others for the proteinase from rat liver but resembles the structure of the simpler archaebacterial proteasome. The possibility of conformational changes associated with the addition of effectors of proteolytic activity has been investigated by sedimentation velocity analysis and dynamic light-scattering measurements. The results provide the first direct evidence for conformational changes associated with the observed positive co-operativity in one component of the peptidylglutamylpeptide hydrolase activity as well as with the stimulation of peptidylglutamylpeptide hydrolase activities by MnCl2. In the latter case, there appears to be a correlation between changes in the shape of the molecule and the effect on activity. KCl and low concentrations of SDS may also act by inducing conformational changes within the complex. Sedimentation-velocity measurements also provide evidence for the formation of intermediates during dissociation of the complex by urea, guanidinium chloride or sodium thiocyanate. Dissociation of the complex either by these agents or by treatment at low pH leads to inactivation of its proteolytic components. The results suggest that activation and inhibition of the various proteolytic activities may be mediated by measurable changes in size and shape of the molecules.

scholarly journals Common epitopes of bovine lens multicatalytic-proteinase-complex subunits

1989 ◽  
Vol 257 (1) ◽  
pp. 265-269 ◽  
Author(s):  
B J Wagner ◽  
J W Margolis
Keyword(s):  
Gel Electrophoresis ◽  
Affinity Purification ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyclonal Antiserum ◽  
Antibody Affinity ◽  
Multicatalytic Proteinase ◽  
Bovine Lens ◽  
The Common ◽  
Multicatalytic Proteinase Complex ◽  
Monospecific Antibodies

Component polypeptides of both the bovine lens and pituitary multicatalytic proteinase complexes demonstrate different immunoreactivities with a polyclonal antiserum raised against the purified pituitary enzyme. Four (Mr 24000, 26000, 34000 and 38000) of eight bands that have been resolved by SDS/polyacrylamide-gel electrophoresis are stained in immunoblot experiments. Monospecific antibodies obtained from this antiserum by affinity purification from the 38000- and 34000-Mr bands of the lens enzyme bound equally well to either band, but showed little or no binding to the 26000- and 24000-Mr bands upon immunoblotting. Antibody affinity-purified from the 24000-Mr band showed comparable binding to the 24000-, 34000- or 38000-Mr band. One explanation of these results is that the 24000-Mr polypeptide is derived from the higher-Mr polypeptide(s) and has lost some of the common immunodeterminants.

Synthetic Inhibitors of the Multicatalytic Proteinase Complex (Proteasome)

1993 ◽  
Vol 47 (4-6) ◽  
pp. 306-313 ◽  
Author(s):  
Sherwin Wilk ◽  
Maria E. Figueiredo-Pereira
Keyword(s):  
Multicatalytic Proteinase ◽  
Multicatalytic Proteinase Complex
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