Rabbit Anti-Human RPF2 Polyclonal Antibody

To better define the roles of assembly factors required for eukaryotic ribosome biogenesis, we have focused on one specific step in maturation of yeast 60 S ribosomal subunits: processing of 27SB pre-ribosomal RNA. At least 14 assembly factors, the 'B-factor' proteins, are required for this step. These include most of the major functional classes of assembly factors: RNA-binding proteins, scaffolding protein, DEAD-box ATPases and GTPases. We have investigated the mechanisms by which these factors associate with assembling ribosomes. Our data establish a recruitment model in which assembly of the B-factors into nascent ribosomes ultimately leads to the recruitment of the GTPase Nog2. A more detailed analysis suggests that this occurs in a hierarchical manner via two largely independent recruiting pathways that converge on Nog2. Understanding recruitment has allowed us to better determine the order of association of all assembly factors functioning in one step of ribosome assembly. Furthermore, we have identified a novel subcomplex composed of the B-factors Nop2 and Nip7. Finally, we identified a means by which this step in ribosome biogenesis is regulated in concert with cell growth via the TOR protein kinase pathway. Inhibition of TOR kinase decreases association of Rpf2, Spb4, Nog1 and Nog2 with pre-ribosomes.

Proteins Rpf2 and Rrs1 are required for 60S ribosomal subunit maturation. These proteins are necessary for the recruitment of three ribosomal components (5S ribosomal RNA [rRNA], RpL5 and RpL11) to the 90S ribosome precursor and subsequent 27SB pre-rRNA processing. Here we present the crystal structure of the Aspergillus nidulans (An) Rpf2-Rrs1 core complex. The core complex contains the tightly interlocked N-terminal domains of Rpf2 and Rrs1. The Rpf2 N-terminal domain includes a Brix domain characterized by similar N-and C-terminal architecture. The long alpha-helix of Rrs1 joins the C-terminal half of the Brix domain as if it were part of a single molecule. The conserved proline-rich linker connecting the N- and C-terminal domains of Rrs1 wrap around the side of Rpf2 and anchor the C-terminal domain of Rrs1 to a specific site on Rpf2. In addition, gel shift analysis revealed that the Rpf2-Rrs1 complex binds directly to 5S rRNA. Further analysis of Rpf2-Rrs1 mutants demonstrated that Saccha-romyces cerevisiae Rpf2 R236 (corresponds to R238 of AnRpf2) plays a significant role in this binding. Based on these studies and previous reports, we have proposed a model for ribosomal component recruitment to the 90S ribosome precursor.