C9orf64 (Chromosome 9 open reading frame 64) is a gene located on chromosome 9, that in humans encodes the protein queuosine salvage protein.[5] The function and biological process of the queuosine salvage protein is a queuosine-nucleotide N-glycosylase/hydrolase (QNG1) that releases queuine from Q-5'-monophosphate, and this activity is required for
the salvage of queuine from exogenous Queuosine by S. pombe and HeLa
cells.[6] Some evidence from orthologs indicates it may be involved in tRNA processing and recycling. The most common mRNA contains 4 coding exons, and it has 2 additional alternatively spliced exons.[5] C9orf64 has been found in 5 different splice variants.[7]
Expression of this gene is highest in the duodenum and small intestine, and it is also expressed in 24 other tissues.[8]
22 variants have been annotated in the NIH Database, ClinVar, linked to disease conditions such as seizures, developmental delay, and muscular hypotonia.[9]
Queuosine salvage protein is 341 amino acids long with a molecular weight of 39,029 daltons and an isoelectric point of 5.61. It is a member of the DUF2419 superfamily.[10][11] The DUF position on the human protein is from amino acid 53 to 341.[10]Bioinformatic tools at ExPASy predicted a second peroxisomal targeting signal.[12] Crystal structures of wild-type human
QNG1 and QNG1 in complex with queuine have been deposited with the
Protein Data Bank under accession numbers 7UGK and 8DL3.[13][14] The DUF position on the human protein is from amino acid 53 to 341.[10]
C9orf64 is located on chromosome 9q21.32.[5] The genes closest to C9orf64 on the long arm of chromosome 9 include GKAP1, KIF27, HNRNPK, RMI1, and a MicroRNA MIR7-1.[15]
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