title: KAI1, a prostate metastasis suppressor: prediction of solvated structure and interactions with binding partners; integrins, cadherins, and cell-surface receptor proteins.
abstract: The solution structure of the transmembrane-4 superfamily protein KAI1, a recently identified prostate cancer metastasis suppressor gene that encodes a 267-amino acid protein, was modeled. The structure of this four-helical transmembrane protein was developed by defining and modeling sections individually. A complete three-dimensional structure for the solvated protein was developed by combining the individually modeled sections. The four-helix transmembrane bundle structure was predicted combining information from several methods including Fourier transform analysis of residue variability for helix orientation. The structure of the KAI1 large extracellular domain was modeled based on the solved crystal structure of the extracellular domain of another tetraspanin superfamily protein member, CD81 (hepatitis C virus envelope E2 glycoprotein receptor). This is a novel protein fold consisting of five alpha helices held together by two disulfide bonds for which the CD81 protein is the first solved representative. Molecular dynamics studies were performed to test stability and to relax the total model KAI1 structure's solution. The resulting KAI1 structural model should be a useful tool for predicting modes of self-association and associations with other TM4SF proteins, integrins, cadherins, and other KAI1 binding partners. Mutations for probing the interactions of KAI1 with antibodies and with other binding partners are suggested. Published 2001 Wiley-Liss, Inc.
authors.affiliation: National Institutes of Health, National Institute of Environmental Health Sciences, Scientific Computing Laboratory, Research Triangle Park, North Carolina 27709, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Bienstock
authors.forename: J C
authors.initials: JC
authors.lastname: Barrett
mesh_terms: D000595:Amino Acid Sequence; D015703:Antigens, CD; D015820:Cadherins / Q000737:chemistry / Q000378:metabolism; D016147:Genes, Tumor Suppressor; D006801:Humans; D016023:Integrins / Q000737:chemistry / Q000378:metabolism; D051861:Kangai-1 Protein; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009362:Neoplasm Metastasis / Q000235:genetics; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D011485:Protein Binding; D011487:Protein Conformation; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D015703:Antigens, CD; C497688:CD82 protein, human; D015820:Cadherins; D016023:Integrins; D051861:Kangai-1 Protein; D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface