U6 snRNA phosphodiesterase Usb1 (IPR027521)

Short name: Usb1

Overlapping homologous superfamilies


Family relationships



Proteins in this family are phosphodiesterases responsible for trimming the poly (U) tract of the last nucleotides in the pre-U6 snRNA molecule, leading to the formation of mature U6 snRNA [PMID: 22899009].

In Saccharomyces cerevisiae, Usb1 is an essential protein that localises to the nucleus and mitochondria [PMID: 14562095]. Usb1 overexpression can compensate for specific respiratory defects of an oxa1 yeast mutant [PMID: 22027258].

In humans, Usb1 is localised to the nucleus and is involved in the 2',3'-cyclic phosphate formation at the 3' end of U6 snRNA [PMID: 22899009]. The human protein has been shown to degrade both oligo(U) and oligo(A) tails at the 3' end of U6 snRNA [PMID: 23190533]. Its crystal structure has been solved and shows a globular alpha-beta-type architecture [PMID: 23190533]. Mutation in Usb1 is linked to poikiloderma with neutropenia (PN), a genodermatosis characterised by poikiloderma, pachyonychia and chronic neutropenia [PMID: 20004881, PMID: 20503306].

GO terms

Biological Process

GO:0034477 U6 snRNA 3'-end processing

Molecular Function

GO:0004518 nuclease activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.