InterPro domain: IPR007834

This family includes yeast Sem1 and its mammalian homologue, DSS1.

Sem1/DSS1 (also known as rpn15) is a component of lid subcomplex of 26S proteasome regulatory subunit [ 1 , 2 , 3 ]. Besides being a subunit of the 26S proteasome, Sem1/DSS1 associates with other protein complexes [ 4 ]. It is a component of the nuclear pore complex (NPC)-associated TREX-2 complex that is required for transcription-coupled mRNA export, and the COP9 signalosome, which is involved in deneddylation [ 5 , 6 , 7 ].

Loss of DSS1 in humans has been associated with split hand/split foot malformations [ 8 ].

1. Localization of the regulatory particle subunit Sem1 in the 26S proteasome. Biochem. Biophys. Res. Commun. 435, 250-4
2. The intrinsically disordered Sem1 protein functions as a molecular tether during proteasome lid biogenesis. Mol. Cell 53, 433-43
3. Sem1p is a novel subunit of the 26 S proteasome from Saccharomyces cerevisiae. J. Biol. Chem. 279, 28807-16
4. DSS1/Sem1, a Multifunctional and Intrinsically Disordered Protein. Trends Biochem. Sci. 41, 446-59
5. BRCA2 prevents R-loop accumulation and associates with TREX-2 mRNA export factor PCID2. Nature 511, 362-5
6. Sem1 is a functional component of the nuclear pore complex-associated messenger RNA export machinery. J. Cell Biol. 184, 833-46
7. CSNAP Is a Stoichiometric Subunit of the COP9 Signalosome. Cell Rep 13, 585-98
8. Split hand/split foot malformation, deafness, and mental retardation with a complex cytogenetic rearrangement involving 7q21.3. J. Med. Genet. 33, 507-10