title: Anti-cathepsin L monoclonal antibodies that distinguish cathepsin L from cathepsin V.
abstract: Cathepsin L is a lysosomal cysteine protease involved in intracellular protein degradation. Recently, several new cysteine proteases have been identified. Human cathepsin V, a thymus- and testis-specific human cysteine protease, shares 78% sequence identity with human cathepsin L. Due to the strong sequence similarity, highly selective reagents are needed to elucidate the physiological functions of the two enzymes. Monoclonal antibodies (mAbs) have been prepared against recombinant human cathepsin L. Antibodies produced by five clones reacted with procathepsin L and mature cathepsin L. They also reacted with cathepsin L in complex with a peptide fragment, which is identical to the alternatively spliced segment of the p41 form of MHC Class II associated invariant chain. Two mAbs, (M105 and H102) were specific for cathepsin L, while three (N135, B145 and D24) cross-reacted with cathepsin V. None of the mAbs cross-reacted with cathepsins B, H and S. We have developed a sandwich enzyme-linked immunosorbent assay (ELISA) for quantifying cathepsin L. This sandwich ELISA uses a combination of two monoclonal antibodies which recognize different, non-overlapping epitopes on the cathepsin L molecule. The lower detection limit of the sandwich ELISA was 5 ng of cathepsin L per ml.
authors.affiliation: Department of Biochemistry and Molecular Biology, Jozef Stefan Institute, Ljubljana, Slovenia.
authors.forename: N
authors.initials: N
authors.lastname: Kopitar-Jerala
authors.forename: T
authors.initials: T
authors.lastname: Bevec
authors.forename: D
authors.initials: D
authors.lastname: Barlic-Maganja
authors.forename: F
authors.initials: F
authors.lastname: Gubensek
authors.forename: V
authors.initials: V
authors.lastname: Turk
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity / Q000276:immunology*; D000944:Antigens, Differentiation, B-Lymphocyte; D056668:Cathepsin L; D002403:Cathepsins / Q000276:immunology*; D003429:Cross Reactions; D003546:Cysteine Endopeptidases; D004792:Enzyme Precursors / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D000949:Histocompatibility Antigens Class II; D006801:Humans; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D017385:Sequence Homology
chemical_list: D000911:Antibodies, Monoclonal; D000944:Antigens, Differentiation, B-Lymphocyte; D004792:Enzyme Precursors; D000949:Histocompatibility Antigens Class II; D010446:Peptide Fragments; C045084:invariant chain; D002403:Cathepsins; D003546:Cysteine Endopeptidases; C063905:procathepsin L; C534281:CTSL protein, human; D056668:Cathepsin L; C117627:CTSV protein, human