Gar1 is a small nucleolar RNP that is required for pre-mRNA processing and pseudouridylation . It is co-immunoprecipitated with the H/ACA families of snoRNAs. This family represents the conserved central region of Gar1. This region is necessary and sufficient for normal cell growth, and specifically binds two snoRNAs snR10 and snR30. This region is also necessary for nucleolar targeting, and it is thought that the protein is co-transported to the nucleolus as part of a nucleoprotein complex . In humans, Gar1 is also component of telomerase in vivo . Naf1 is an essential protein that plays a role in ribosome biogenesis, modification of spliceosomal small nuclear RNAs and telomere synthesis, and is homologous to Gar1 .
H/ACA ribonucleoprotein particles (RNPs) are a family of RNA pseudouridine synthases that specify modification sites through guide RNAs. The function of these H/ACA RNPs is essential for biogenesis of the ribosome, splicing of precursor mRNAs (pre-mRNAs), maintenance of telomeres and probably for additional cellular processes [PUBMED:16647858]. All H/ACA RNPs contain a specific RNA component (snoRNA or scaRNA) and at least four proteins common to all such particles: Cbf5, Gar1, Nhp2 and Nop10. These proteins are highly conserved from yeast to mammals and homologues are also present in archaea [PUBMED:10871366]. The H/ACA protein complex contains a stable core composed of Cbf5 and Nop10, to which Gar1 and Nhp2 subsequently bind [PUBMED:19917616].
Dragon F, Pogacic V, Filipowicz W; , Mol Cell Biol 2000;20:3037-3048.: In vitro assembly of human H/ACA small nucleolar RNPs reveals unique features of U17 and telomerase RNAs. PUBMED:10757788 EPMC:10757788 .
Leulliot N, Godin KS, Hoareau-Aveilla C, Quevillon-Cheruel S, Varani G, Henry Y, Van Tilbeurgh H;, J Mol Biol. 2007;371:1338-1353.: The box H/ACA RNP assembly factor Naf1p contains a domain homologous to Gar1p mediating its interaction with Cbf5p. PUBMED:17612558 EPMC:17612558.