title: The beta-isoform of heat shock protein hsp-90 is structurally related with human microtubule-interacting protein Mip-90.
abstract: Through major research advances in the study of cytoskeletal organization, an integrated view of the complexity of this system has emerged. Recent findings on the microtubule-interacting protein Mip-90, which associates with microtubules and actin filaments in different cell domains, have shed light on its roles in cytoskeletal regulation. In order to study structural features of Mip-90, we sequenced several peptide fragments. A comparative sequence analysis revealed a high degree of similarity between the primary structure of this protein and the human heat shock protein of 90 kDa (hsp-90). Taken together, the present studies indicate the identity between Mip-90 and the the beta-isoform of hsp-90 (hsp-90beta). Western blot assays with an anti-hsp-90 monoclonal antibody showed cross-reactivity of hsp-90 and Mip-90 affinity purified from HeLa cells. Furthermore, the observed structural identity of Mip-90 with the hsp-90beta was sustained by immunoblot assays using monoclonal antibodies that specifically recognize the alpha- and beta-forms of hsp-90. Comparative fingerprinting analysis, along with the evidence of a remarkably similar biochemical behavior of both hsp-90 and Mip-90 in different affinity chromatographic systems, supported these observations. These studies, along with previous investigations, provide new data to elucidate the functional significance of these interesting cellular components and its relationships with other proteins linked to the cell architecture.
authors.affiliation: Laboratory of Cellular and Molecular Biology, Faculty of Sciences, University of Chile and International Center for Cancer and Developmental Biology (ICC), Las Palmeras 3425, Nuñoa, Santiago, Chile.
authors.forename: V
authors.initials: V
authors.lastname: Cambiazo
authors.forename: M
authors.initials: M
authors.lastname: González
authors.forename: C
authors.initials: C
authors.lastname: Isamit
authors.forename: R B
authors.initials: RB
authors.lastname: Maccioni
mesh_terms: D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D005347:Fibroblasts / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D008840:Microfilament Proteins / Q000276:immunology; D008869:Microtubule-Associated Proteins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D010449:Peptide Mapping; D020033:Protein Isoforms; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D018841:HSP90 Heat-Shock Proteins; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; C111403:Mip-90 protein, human; D020033:Protein Isoforms; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase