InterPro domain: IPR039912

Pre-rRNA-processing protein PNO1 is also known as Partner of NOB1 and ribosomal RNA-processing protein 20. NOB1 is a nuclear protein that forms a complex with the 19S regulatory particle of the 26S proteasome and PNO1, acting as a chaperone to join the 20S proteasome with the 19S regulatory particle. The NOB1 complex is then degraded by the mature 26S proteasome [ 1 ]. PNO1 is also a component of the pre-ribosomal particle, and strains lacking PNO1 are defective in ribosomal RNA processing [ 2 ]. PNO1 remains a component of the SSU RRP complex, in which pre-40S subunits are left associated with a limited set of proteins [ 3 ]. PNO1 contains a K Homology domain.

1. Nob1p is required for biogenesis of the 26S proteasome and degraded upon its maturation in Saccharomyces cerevisiae. Genes Dev. 16, 3142-57
2. RRP20, a component of the 90S preribosome, is required for pre-18S rRNA processing in Saccharomyces cerevisiae. Nucleic Acids Res. 31, 2524-33
3. Dim2p, a KH-domain protein required for small ribosomal subunit synthesis. RNA 10, 645-56