Ribosome biogenesis protein Nsa1 (Nop7-associated 1) from fungi is an essential factor for ribosome assembly. In cooperation with the assembly factor Rix7, Nsa1 participates in an early cleavage of the pre-rRNA processing pathway. Rix7 is a type II double ring, AAA-ATPase, that may mediate the release of Nsa1 from nucleolar pre-60S particles. The release of Nsa1 from a discrete preribosomal particle may trigger the progression of 60S ribosome biogenesis. Nsa1 is essential for cell viability in yeast. It contains an N-terminal seven-bladed beta-propeller WD40 domain that associates with the D1-AAA domain of the AAA-ATPase Rix7, and a flexible lysine-rich C-terminus that extends outward from the WD40 domain, and is required for nucleolar localization.
Jiyao W et al.(2023). "The conserved domain database in 2023.",