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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, METHODS. Meshes: Amino Acid Sequence, Amino Acids, Antibodies, Monoclonal, Antigens, Polyomavirus Transforming, Binding Sites, Cell Line, Cell Transformation, Viral, Cullin Proteins, Epitopes, Humans, Immunoprecipitation, Mutation, Protein Binding, Protein Interaction Domains and Motifs, Protein-Serine-Threonine Kinases.
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Do sV40 T-Antigen Amino Acid Changes that Disrupt Cul-7 or Bub-1 Binding Do Not Globally Distort the T-Common Region? Context: Amino acids 1-107 of the SV40 T antigen constitute a functionally important and complex region. Cellular proteins, Hsc70, Bub-1, Cul-7, and Rb, each of which is involved in cell growth control or genomic stability, bind within this portion of the T antigen. Mutational analysis has mapped the J domain/Hsc70, Bub-1, and the Rb binding motifs. Two regions of the T antigen have been implicated in Cul-7 binding. Mutation of F98A diminished Cul-7 binding, and deletion of amino acids 68-83 abolished it. The authors suggest, based on T-antigen structure, that F98 is inaccessible and that the F98A change altered the configuration of the upstream region, preventing Cul-7 binding. Our objective was to determine, by using monoclonal T-antigen antibodies, whether F98 is accessible and whether F98A substitution globally distorted the T-common region. Cell-expressing T antigens, immunoprecipitation, and immunoblot were used to determine the accessibility of amino acids.
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Full-length T-antigen and N-terminal fragments containing F98A were immunoprecipitated by monoclonal antibody PAb902, which recognizes a conformation-dependent epitope within the first 82 amino acids. Therefore, this alteration does not globally distort the entire T-common region. Additionally, PAb416, which displaces Cul-7 from the T antigen and immunoprecipitates bound pRb peptides, depends on F98 for binding, implying that amino acid 98 is part of the epitope and accessible in the native T antigen. Final Decision: yes