Yeast L dsRNA consists of at least three distinct RNAs; evidence that the non-Mendelian genes [HOK], [NEX] and [EXL] are on one of these dsRNAs.

[HOK], [NEX] and [EXL] are non-Mendelian genes affecting the K1 and K2 killer systems of Saccharomyces cerevisiae. T1 fingerprints of L double-stranded RNA from [HOK]-, [NEX]- and [EXL]-containing cells and their heat-cured derivatives indicate that: there are three distinct double-stranded RNAs, L-A, L-B and L-C; [HOK], [NEX] and [EXL] are all located on L-A; there are three functional variants of L-A that produce the [HOK] [NEX], [HOK] [EXL] or [EXL] phenotypes; L-A is compatible with L-B or L-C; and there are additional sequences present in lower copy number. Although their fingerprint patterns are unrelated, solution hybridization shows that L-B and L-C share sequence homology. Strains carrying L-A as the major double-stranded RNA or only L-B or only L-C all have similarly sedimenting (160S) virus-like particles with RNA polymerase activity. Virus-like particles from strains with L-A all have proteins of 81,000 and 180,000 daltons that are absent from isogenic strains cured of L-A. Virus-like particles from strains with only L-B or only L-C both have major proteins of 77,000 and 73,000 daltons.