A Noc complex specifically involved in the formation and nuclear export of ribosomal 40 S subunits.
Formation and nuclear export of 60 S pre-ribosomes requires many factors including the heterodimeric Noc1-Noc2 and Noc2-Noc3 complexes. Here, we report another Noc complex with a specific role in 40 S subunit biogenesis. This complex consists of Noc4p, which exhibits the conserved Noc domain and is homologous to Noc1p, and Nop14p, a nucleolar protein with a role in 40 S subunit formation. Moreover, noc4 thermosensitive mutants are defective in 40 S biogenesis, and rRNA processing is inhibited at early cleavage sites A(0), A(1), and A(2). Using a fluorescence-based visual assay for 40 S subunit export, we observe a strong nucleolar accumulation of the Rps2p-green fluorescent protein reporter in noc4 ts mutants, but 60 S subunit export was normal. Thus, Noc4p and Nop14p form a novel Noc complex with a specific role in nucleolar 40 S subunit formation and subsequent export to the cytoplasm.
Milkereit
Philipp
P
Biochemie-Zentrum Heidelberg, Im Neuenheimer Feld 328, Germany.
Strauss
Daniela
D
Bassler
Jochen
J
Gadal
Olivier
O
Kühn
Holger
H
Schütz
Sylvia
S
Gas
Nicole
N
Lechner
Johannes
J
Hurt
Ed
E
Tschochner
Herbert
H
D000595:Amino Acid Sequence; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism*; D002846:Chromatography, Affinity; D017931:DNA Primers; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; C472292:Noc4 protein, S cerevisiae; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins