Related Experiment Video
Updated: Jul 31, 2026

The Importance of Correct Protein Concentration for Kinetics and Affinity Determination in Structure-function Analysis
Published on: March 18, 2010
The multicatalytic proteinase complex
1Department of Biochemistry, University of Leicester, U.K.
Abstract:
The multicatalytic proteinase is a soluble nonlysosomal proteinase of Mr congruent to 700,000. It is composed of at least ten different types of subunit arranged as a stack of four rings in a hollow cylindrical structure. It is similar, if not identical, to prosomes and has also been referred to as the proteasome. The proteinase degrades some protein, peptide and synthetic peptide substrates. It is inhibited by thiol-reactive reagents and by peptide aldehydes. Results of studies with these inhibitors and of mixed-substrate experiments suggest that the proteinase molecule has at least two distinct types of proteolytic sites which have different specificities for peptide substrates. Antibodies raised against the native proteinase precipitate the complex but do not inhibit its proteolytic activities, and recognize only a few of the subunits on Western blots.
Related Concept Videos
Protein Complex Assembly
Many viruses self-assemble into a fully functional unit using the infected host cell to...
Protein Complexes with Interchangeable Parts
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
The Proteasome
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. A series of enzymes carry out the ubiquitination of the target proteins - E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3...
Protein Complex Assembly
Many viruses self-assemble into a fully functional unit using the infected host cell to...
The Proteasome
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...
The Proteasome Structure
The proteasome is an...

