title: Multiple high activity cysteine proteases of Leishmania mexicana are encoded by the Imcpb gene array.
abstract: The interrelationship of the multiple cysteine proteases (CPs) found characteristically at high activity in Leishmania mexicana amastigotes has been investigated. The mature forms of the five enzymes of groups B and C, which have subtly different substrate preferences, are the same size. Enzymically deglycosylated group A CP proteins also have the same molecular mass. Proteases of all three groups are specifically recognized by antisera raised against the group B or group C CPs. In addition, CPs of groups A, B and C have highly similar N-terminal amino acid sequences. The consensus sequence matches that predicted from the sequenced Imcpb gene, which occurs in a tandem array of over ten similar genes. Thus, the results are consistent with the groups A, B and C CPs being products of different Imcpb genes within the array, the different genes encoding CPs with identical N-termini, but with limited amino acid substitutions within the mature enzyme accounting for the different properties of the CPs. Evidence is also presented to indicate membrane-association of proteolytically active but less processed forms of Imcpb products.
authors.affiliation: Department of Zoology, University of Glasgow, UK.
authors.forename: C D
authors.initials: CD
authors.lastname: Robertson
authors.forename: G H
authors.initials: GH
authors.lastname: Coombs
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016384:Consensus Sequence; D003546:Cysteine Endopeptidases / Q000235:genetics* / Q000378:metabolism; D017125:Genes, Protozoan; D007894:Leishmania mexicana / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D015800:Protozoan Proteins; D003546:Cysteine Endopeptidases