High impact information on MAK21

• Using a yeast genetic screen, we have identified Noc3p (nucleolar complex-associated protein) as a novel replication-initiation protein [1].
• Here we show that Sir2 executes these functions as a component of a nucleolar complex designated RENT (regulator of nucleolar silencing and telophase exit) [2].
• Instead, Paf1 loss altered poly(A) site utilization of primary target genes SDA1 and MAK21, resulting in increased abundance of 3'-extended mRNAs [3].
• We cloned MAK21 using its map location and found that Mak21p is homologous to a human and mouse CAATT-binding protein and open reading frames in Schizosaccharomyces pombe and Caenorhabditis elegans [4].
• Although the human protein regulates Hsp70 production, Mak21p is essential for growth and necessary for 60 S ribosomal subunit biogenesis. mak21-1 mutants have decreased levels of L-A coat protein and L-A double-stranded RNA [4].

Biological context of MAK21

• Mak21p of Saccharomyces cerevisiae, a homolog of human CAATT-binding protein, is essential for 60 S ribosomal subunit biogenesis [4].
• Overexpression of a conserved domain common to Noc1p and Noc3p is dominant-negative for cell growth, with a defect in nuclear 60S subunit transport, but no inhibition of pre-rRNA processing [5].
• We designated the lesion responsible for the rRNA-processing defect rrp1 and showed that it is located on the right arm of chromosome IV either allelic to or tightly linked to mak21 [6].

Anatomical context of MAK21

• Here, we report three nucleolar proteins, Noc1p to Noc3p, that are required for ribosome maturation and transport [5].

References