Abstract
Proteasomes interact with a variety of macromolecular ligands that modulate their ability to degrade peptide and protein substrates. The effector PA28 increases the peptidase activities of proteasomes whereas HSP90 and alpha-crystallin inhibit a peptide-hydrolyzing activity. Four monoclonal antibodies were used as probes to detect conformational changes of proteasome subunits. Conformational changes in alpha- or beta-subunits were found upon binding PA28, HSP90, alpha-crystallin, and the substrate casein but not with the peptide substrate analogs calpain inhibitor 1 (Ac-Leu-Leu-norleucinal), calpain inhibitor 2 (Ac-Leu-Leu-methioninal), or MG 132 (N-Cbz-Leu-Leu-leucinal).
Copyright 1999 Academic Press.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Animals
-
Antibodies, Monoclonal / immunology*
-
Antibody Affinity
-
Binding Sites, Antibody
-
Caseins / metabolism
-
Crystallins / metabolism
-
Cysteine Endopeptidases / chemistry*
-
Cysteine Endopeptidases / immunology
-
Cysteine Endopeptidases / metabolism*
-
Cysteine Proteinase Inhibitors / metabolism
-
Enzyme-Linked Immunosorbent Assay
-
Glycoproteins / metabolism
-
HSP90 Heat-Shock Proteins / metabolism
-
Humans
-
Leupeptins / metabolism
-
Ligands
-
Multienzyme Complexes / chemistry*
-
Multienzyme Complexes / immunology
-
Multienzyme Complexes / metabolism*
-
Muscle Proteins*
-
Oligopeptides / metabolism
-
Proteasome Endopeptidase Complex
-
Protein Conformation
-
Proteins / metabolism
Substances
-
Antibodies, Monoclonal
-
Caseins
-
Crystallins
-
Cysteine Proteinase Inhibitors
-
Glycoproteins
-
HSP90 Heat-Shock Proteins
-
Leupeptins
-
Ligands
-
Multienzyme Complexes
-
Muscle Proteins
-
Oligopeptides
-
PSME1 protein, human
-
Proteins
-
calpain inhibitors
-
calpain inhibitor 2
-
Cysteine Endopeptidases
-
Proteasome Endopeptidase Complex
-
benzyloxycarbonylleucyl-leucyl-leucine aldehyde