A pre-ribosome-associated HEAT-repeat protein is required for export of both ribosomal subunits.
Rrp12p (Ypl012w) is unusual among characterized ribosome synthesis factors in being associated with late precursors to both the 40S and 60S subunits. Rrp12p is predominantly nuclear with nucleolar enrichment at steady state, but shuttled between the nucleus and cytoplasm in a heterokaryon assay. Strains depleted of Rrp12p are impaired in the nuclear export of both ribosomal subunits. Sequence analysis combined with fold recognition and modeling showed that Rrp12p is a member of a family of pre-ribosome-associated HEAT-repeat proteins. Like other HEAT-repeat transport factors, Rrp12p binds in vitro to nucleoporin FG-repeats of both the GLFG and FXFG families and to the GTPase Gsp1p (yeast RAN). Rrp12p also showed robust in vitro binding to a pre-rRNA transcript, in addition to poly(A) and poly(U). We propose that Rrp12p binds to the RNA components of the pre-ribosomes and promotes export of both subunits via its interactions with the nucleoporins and Gsp1p.
Oeffinger
Marlene
M
Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK.
Dlakic
Mensur
M
Tollervey
David
D
D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012337:RNA, Ribosomal, 18S / Q000096:biosynthesis; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D017422:Sequence Analysis, DNA
C080324:GSP1 protein, S cerevisiae; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D012337:RNA, Ribosomal, 18S; C481980:Rrp12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D020559:Monomeric GTP-Binding Proteins