Isolation and characterization of a novel ribonucleoprotein particle: large structures contain a single species of small RNA.

摘要: Rat liver coated vesicle preparations were frequently found to contain small ovoid bodies, which resembled vesicles in morphology. We have purified these bodies homogeneity using sucrose density gradients and preparative agarose gel electrophoresis. When negatively stained viewed by electron microscopy, the structures display a very distinct complex morphology, resembling multiple arches form cathedral vaults. They measure 35 X 65 nm are therefore considerably larger than ribosomes. subjected SDS PAGE, structures, we refer as vaults, appear several minor five major species: Mr 210,000, 192,000, 104,000, 54,000, 37,000. One of (Mr 104,000) greatly predominates, accounting for greater 70% total Coomassie Brilliant Blue-staining protein. Another species 37,000 has been identified RNA unusual base composition (adenosine 12.0%, guanosine 29.7%, uridine 30.9%, 27.4% cytidine), migrates single urea PAGE between 5S 5.8S ribosomal standards, containing approximately 140 bases. Although constitutes only 4.6% entire structure, large size particle requires that each one contains 9 molecules this RNA. Antibodies prepared against largely specific polypeptide species. they do not directly react with constituent on Western blots, antibodies immunoprecipitate 32P-labeled identical from metabolically-labeled rat hepatoma cells. Vaults observed partially fractions human fibroblasts, murine 3T3 cells, glial rabbit alveolar macrophages. It appears novel ribonucleoprotein broadly distributed among different cell types. The function vaults is at present unknown.