title: Purification of the complex of cathepsin L and the MHC class II-associated invariant chain fragment from human kidney.
abstract: The complex of cathepsin L and the fragment of the MHC class II-associated invariant chain was purified from human kidney. M(r) of the complex, as determined by gel filtration, is about 40,000. Both components were identified by amino acid and sequence analyses. The bound invariant chain fragment is almost identical to the additional segment found in p41, but not in the p31 form of the invariant chain. The complex has significantly enhanced stability at neutral and slightly alkaline pH, and reduced proteolytic activity against the synthetic substrate Z-Phe-Arg-MCA compared to free cathepsin L. The complex exhibits no enzymatic activity against the protein substrate azocasein. For the first time, the invariant chain was found in a complex with a protein, which was not an MHC molecule.
authors.affiliation: Department of Biochemistry and Molecular Biology, Jozef Stefan Institute, Ljubljana, Slovenia.
authors.forename: T
authors.initials: T
authors.lastname: Ogrinc
authors.forename: I
authors.initials: I
authors.lastname: Dolenc
authors.forename: A
authors.initials: A
authors.lastname: Ritonja
authors.forename: V
authors.initials: V
authors.lastname: Turk
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D056668:Cathepsin L; D002403:Cathepsins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003546:Cysteine Endopeptidases; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases; D006681:HLA-D Antigens / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D006801:Humans; D007525:Isoelectric Focusing; D007668:Kidney / Q000201:enzymology* / Q000276:immunology*; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D011485:Protein Binding; D013050:Spectrometry, Fluorescence
chemical_list: D006681:HLA-D Antigens; D046911:Macromolecular Substances; D010446:Peptide Fragments; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L