Table 1.

Protein Subunits of the Eukaryotic Exosome and Their Archaeal Counterparts

Eukaryotic subunit (yeast) Activity Domain architecture Archaeal ortholog (non-orthologous homolog)
Sso Ap Af Ph/Pa Mj Mth
Core subunits
 Rrp41p/Ski6p3′–5′ exonucleaseRNase PH6015742APE1447AF0493PH1549/PAB0420—MTH683
 Rrp42pRNase PH6015744APE1445AF0494PH1548/PAB0421—MTH682
 Rrp43pRNase PH(6015744)(APE1445)(AF0494)(PH1548/PAB0421)—(MTH682)
 Rrp44p/Dis3pPIN + RNase II + S1——————
 Rrp45pRNase PH(6015744)(APE1445)(AF0494)(PH1548/PAB0421)—(MTH682)
 Rrp46pRNase PH(6015742)(APE1447)(AF0493)(PH1549/PAB0420)—(MTH683)
 Mtr3pRNase PH(6015742)(APE1447)(AF0493)(PH1549/PAB0420)—(MTH683)
 Rrp4pRNA-binding; 3′–5′  exonuclease??S1 + KH6015740APE1448AF0492PH1551/PAB0419—MTH684
 Rrp40pRNA-bindingS1 + KH(6015740)(APE1448)(AF0492)(PH1551/PAB0419)—(MTH684)
 Cs14pRNA-bindingS1 + (Zn-ribbon)??APE0445AF0206PH1551/PAB0419—MTH1318
Nuclear subunit
 Rrp6p3′–5′ exonucleaseRNase D + HRDC——————
Associated factors
 Mtr4pRNA helicaseSFII helicase??(APE0191)(AF2245)(PH1280)(MJ1124)(MTH810)
 Ski2pSFII helicase??(APE0191)(AF2245)(PH1280)(MJ1124)(MTH810)
 Ski3pTPR ??????
 Ski8pWD40——————