title: Electron microscopy of U1 small nuclear ribonucleoprotein particles: shape of the particle and position of the 5' RNA terminus.
abstract: Small nuclear ribonucleoprotein particles U1 (U1 snRNPs) from HeLa cells were purified to homogeneity and examined in the electron microscope by negative staining with the double carbon film technique. A survey of several hundred views of the U1 snRNP particles revealed a main body about 8 nm in diameter with two characteristic protuberances 4-7 nm long and 3-4 nm wide. Anti-m3G antibodies were then used to define the site of the m3G base in the 5' cap of the U1 snRNA, close to the site where base-pairing occurs with the 5' splice sequence of pre-mRNA. The m3G base is located on the body of the U1 snRNP, close to one of the protuberances and approximately opposite the other.
authors: Max-Planck-Institut für Molekulare Genetik, Otto Warburg Laboratories, Berlin, FRG.
authors: B
authors: B
authors: Kastner
authors: R
authors: R
authors: Lührmann
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D000939:Epitopes / Q000032:analysis; D006367:HeLa Cells / Q000032:analysis; D006801:Humans; D008854:Microscopy, Electron; D012342:RNA, Small Nuclear / Q000648:ultrastructure; D012261:Ribonucleoproteins / Q000276:immunology / Q000302:isolation & purification / Q000648:ultrastructure*; D017411:Ribonucleoproteins, Small Nuclear
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D012342:RNA, Small Nuclear; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear