Pathways & interactions
Small-subunit processome, Utp12 (IPR007148)
Short name: SSU_processome_Utp12
A large ribonuclear protein complex is required for the processing of the small-ribosomal-subunit rRNA - the small-subunit (SSU) processome [PMID: 12068309, PMID: 15590835]. This preribosomal complex contains the U3 snoRNA and at least 40 proteins, which have the following properties:
- They are nucleolar.
- They are able to coimmunoprecipitate with the U3 snoRNA and Mpp10 (a protein specific to the SSU processome).
- They are required for 18S rRNA biogenesis.
There appears to be a linkage between polymerase I transcription and the formation of the SSU processome; as some, but not all, of the SSU processome components are required for pre-rRNA transcription initiation. These SSU processome components have been termed t-Utps. They form a pre-complex with pre-18S rRNA in the absence of snoRNA U3 and other SSU processome components. It has been proposed that the t-Utp complex proteins are both rDNA and rRNA binding proteins that are involved in the initiation of pre18S rRNA transcription. Initially binding to rDNA then associating with the 5' end of the nascent pre18S rRNA. The t-Utpcomplex forms the nucleus around which the rest of the SSU processome components, including snoRNA U3, assemble [PMID: 15489292]. From electron microscopy the SSU processome may correspond to the terminal knobs visualized at the 5' ends of nascent 18S rRNA.
This domain is found at the C terminus of proteins containing WD40 repeats. These proteins are part of the U3 ribonucleoprotein. In yeast, these proteins are called Utp5, Utp1 or Pwp2, Utp12 or DIP2 Q12220. They interact with snoRNA U3 and with MPP10 [PMID: 12068309]. Pwp2 is an essential Saccharomyces cerevisiae (Baker's yeast) protein involved in cell separation.
- PF04003 (Utp12)