title: Characterization of the nucleolar protein, B-36, using monoclonal antibodies.
abstract: A panel of nine monoclonal antibodies has been produced against a major nuclear protein, B-36, purified from the slime mold Physarum polycephalum. B-36, a 34 kD protein biochemically similar to the major structural proteins of mammalian hnRNP particles, was previously shown to be largely associated with the nucleolus. Eight of the monoclonal antibodies are specific for B-36 protein in Physarum and at least three different epitopes are represented among these eight. Using the monoclonal antibodies B-36 has been shown to be localized exclusively to the nucleolus in actively-growing Physarum cultures. The nucleolar localization of B-36 is dependent on the presence of intact RNA, but not DNA, supporting the hypothesis that B-36 is associated with nucleolar RNA, possibly in some analogous manner to the interaction of the related proteins within heterogeneous nuclear ribonucleoproteins (hnRNP) particles. B-36 is apparently a highly conserved nucleolar protein in eukaryotes as all eight of the monoclonal antibodies specific for B-36 in Physarum are also specific for a 34.5 kD nucleolar protein in rat liver. This indicates that a minimum of three distinct epitopes are conserved in B-36 protein from slime mold to rat.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D002466:Cell Nucleolus / Q000032:analysis*; D003429:Cross Reactions; D000939:Epitopes; D005656:Fungal Proteins / Q000032:analysis*; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D008099:Liver / Q000032:analysis; D008970:Molecular Weight; D009687:Nuclear Proteins; D000090243:Nucleophosmin; D010804:Physarum / Q000032:analysis*; D012331:RNA, Fungal / Q000032:analysis; D051381:Rats; D012261:Ribonucleoproteins / Q000032:analysis* / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D005656:Fungal Proteins; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D009687:Nuclear Proteins; D012331:RNA, Fungal; D012261:Ribonucleoproteins; D000090243:Nucleophosmin