Analysis of csn6 and csn7b genes and proteins. (A) The csn6 and csn7b genes were disrupted in diploid S. pombe cells by inserting the ura4 marker. Diploids were sporulated and spore viability was examined by tetrad analysis. Only two spores were viable, indicating that csn6 and csn7b are essential. (B) Cell lysate from a strain carrying csn7b modified with five C-terminal pro-A tags and a TEV cleavage site at the endogenous genomic locus was absorbed to IgG resin, followed by elution of bound proteins with TEV protease (left panel) or SDS (right panel). Gels were stained with Coomassie Brilliant Blue, and proteins were identified by MALDI-TOF mass spectrometry. The asterisks denote degradation products of elF3c.