RIG2, A RING FINGER PROTEIN THAT INTERACTS WITH THE KIN28 CCL1 CTD KINASE IN YEAST/

Kin28/Ccl1, a cyclin-dependent kinase, is essential for the in vivo ph osphorylation of the C-terminal domain of the largest subunit of RNA p olymerase II in Saccharomyces cerevisiae. In a search for mutations co -lethal with a thermosensitive kin28 mutation, we have identified gene s whose products interact functionally with Kin28. In the present work , we have studied a new complementation group of synthetic lethal muta tions. The corresponding gene, RIG2, encodes a predicted RING finger p rotein. Rig2 is likely to be a homolog of MAT1 of higher eukaryotes wh ich forms a ternary complex with MO15(cdk7) and cyclin H. Our genetic data suggest that Rig2 is a component of transcription factor TFIIH. T ranscription activity in a rig2-ts mutant is impeded at restrictive te mperature. However, none of the rig2-ts mutants obtained was UV sensit ive, suggesting that Rig2 is dispensable for nucleotide excision repai r.