Ski complex

The Ski complex is a multi-protein complex involved in the 3' end degradation of messenger RNAs in yeast. The complex consists of three main proteins, the RNA helicase "Ski2" and the proteins "Ski3" and "Ski8". This tetramer contains a 370 kDa core complex, containing N-terminal arms and C-terminal arms from "Ski3". The helicase core of "Ski2" is positioned by both the C-terminal of "Ski3" and two subunits of "Ski8". Helicase activities are initiated by the N-terminal arm and the "Ski2" insertion domain. In yeast, the complex guides RNA molecules to the exosome complex for degradation via a fourth protein, called "Ski7", which contains a GTPase-like protein. "Ski7" involves the 3’ to 5’ degradation of RNA through two different pathways, 3’ poly(A) tail shortening and the binding of the "Ski2", "Ski3", and "Ski8" tetramer and the exosome. The complex consists of three main proteins, the RNA helicase "Ski2" and the proteins "Ski3" and "Ski8". This tetramer contains a 370 kDa core complex, containing N-terminal arms and C-terminal arms from "Ski3". Degradation of the 3' mRNA overhang occurs by association with the 80s ribosome. The 3' end of the mRNA is threaded through the ribosome to "Ski2", preparing it for the degradation process. The helicase core of "Ski2" is positioned by both the C-terminal of "Ski3" and two subunits of "Ski8". Helicase activities are initiated by the N-terminal arm and the "Ski2" insertion domain. Biochemical studies also show that the Ski complex can thread RNA through the exosome complex, thereby coupling the Ski2 protein helicase function with the exoribonuclease activity, leading to degradation of the RNA strand. 