A new mutant form of the ribosomal protein L21 in the fungus Podospora anserina: identification of the structural gene for this protein.

A muation in the cyR1 gene of the fungus Podospora anserina confers resistance to cycloheximide and leads to an alteration of the 60S ribosomal protein L21 (Bégueret et al. 1977). Nine revertants of this mutant were isolated and the properties of these strains were analyzed. It was found that one revertant strain contains a new mutant form of L21. It is proposed that cyR1 gene is the structural gene for protein L21 and that the alteration of this protein is responsible for the resistance to cycloheximide in vivo.