In
molecular biology, the small nucleolar RNA SNORA73 (also called U17/E1 RNA) belongs to the H/ACA class of
small nucleolar RNAs (snoRNAs). Vertebrate U17 is
intron-encoded and ranges in length from 200-230
nucleotides, longer than most snoRNAs. It is one of the most abundant snoRNAs in
human cells and is essential for the cleavage of pre-
rRNA within the 5' external transcribed spacer (ETS).[1] This cleavage leads to the formation of 18S rRNA. Regions of the U17 RNA are complementary to rRNA and act as guides for RNA/RNA interactions, although these regions do not seem to be well conserved between organisms.[2]
There is evidence that SNORA73 (isoforms: SNORA73A and SNORA73B) functions as a regulator of chromatin function.[3] SNORA73 is chromatin-associated RNA (caRNA) and stably linked to chromatin.[4] Notably, SNORA73 can bind to PARP1, leading to the activation of its ADPRylation (PAR) function.[5] SNORA73 Interacts with the PARP1 DNA-Binding Domain. In addition, the snoRNA-activated PARP1 ADPRylates DDX21 in cells to promote cell proliferation.[6]