A yeast antiviral protein, SKI8 , shares a repeated amino acid sequence pattern with β‐subunits of G proteins and several other proteins

SKI8 is a yeast antiviral gene, essential for controlling the propagation of M double‐stranded RNA (dsRNA) and thus for preventing virus‐induced cytopathology. Our DNA sequence of SKI8 shows that it encodes a 397 amino acid protein containing two copies of a 31 amino acid repeat pattern first identified in mammalian β‐transducin and Cdc4p of yeast. There are also four copies of this repeat in yeast Mak11p, necessary for M dsRNA propagation, and three copies in the putative product of the Dictyostelium AAC3 gene. Analysis of 36 cases of the repeat unit shows they have a consensus predicted structure: N–helix–sheet–turn–sheet–turn–sheet–helix–C.