This group represents ribosomal RNA assembly protein KRR1, required for 40S ribosome biogenesis. It is involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly in Saccharomyces cerevisiae [, ]. In Schizosaccharomyces pombe it is known as Mis3 [].
The budding yeast KRR1-interacting protein 1 (Kri1) is an essential nucleolar protein required for 40S ribosome biogenesis []. This entry also includes Kri1 homologues from animals and plants. Their function is not clear.
This entry represents the first K homology domain (KH1) in the KRR1 and Dim2 (Pno1) proteins.Krr1 and Dim2 are structurally related ribosomal assembly factors, present on the 90S pre-ribosome []. They both belong to the family of RNA binding domains that contain K homology (KH) domains. Dim2 and Krr1 each contain two sequential KH domains (KH1 and KH2), but the N and C-terminal extensions differ between the two proteins []. The two KH domains are evident in the structure of KKr1 from Saccharomyces Cerevisiae [].The KH1 domains in Krr1 and Dim2 lack the typical GXXG RNA binding motif and are involved, instead, in protein-protein interactions. The KH1 domain in Krr1 interacts with the nucleolar assembly factor Kri1 and the KH1 domain of Dim2 interacts with the endonuclease Nob1 [].
