Functional modules in ribosomal protein L5 for ribonucleoprotein complex formation and nucleocytoplasmic transport.
Ribosomal protein L5 forms a small, extraribosomal complex with 5 S ribosomal RNA, referred to as the 5 S ribonucleoprotein complex, which shuttles between nucleus and cytoplasm in Xenopus oocytes. Mapping elements in L5 that mediate nuclear protein import defines three separate such activities (L5-nuclear localization sequence (NLS)-1, -2, and -3), which are functional in both oocytes and somatic cells. RNA binding activity involves N-terminal as well as C-terminal elements of L5. In contrast to the full-length protein, none of the individual NLSs carrying L5 fragments are able to allow for the predominating accumulation in the nucleoli that is observed with the full-length protein. The separate L5-NLSs differ in respect to two activities. Firstly, only L5-NLS-1 and -3, not L5-NLS-2, are capable of promoting the nuclear transfer of a heterologous, covalently attached ribonucleoprotein complex. Secondly, only L5-NLS-1 is able to bind strongly to a variety of different import receptors; those that recognize L5-NLS-2 and -3 have yet to be identified.
Claussen
M
M
Institut für Biochemie und Molekulare Zellbiologie, Georg-August-Universität, Humboldtallee 23, D-37073 Göttingen, Germany.
Rudt
F
F
Pieler
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D028884:Karyopherins; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals / Q000235:genetics / Q000502:physiology; D009687:Nuclear Proteins / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D011485:Protein Binding; D012341:RNA, Ribosomal, 5S / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D035582:Transcription Factor TFIIIA; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014981:Xenopus; D028901:alpha Karyopherins; D020931:ran GTP-Binding Protein / Q000378:metabolism
D004268:DNA-Binding Proteins; C466996:IPO7 protein, human; D028884:Karyopherins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D012341:RNA, Ribosomal, 5S; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D012261:Ribonucleoproteins; D012269:Ribosomal Proteins; D035582:Transcription Factor TFIIIA; D014157:Transcription Factors; D028901:alpha Karyopherins; C029742:ribosomal protein L5; D020931:ran GTP-Binding Protein