zone sedimentation analyses of cytoplasmic ribosomes isolated from the wild-type strain and from 14 of the mutant strains grown at 10 c indicate that one cold-sensitive mutant is defective in ribosome biosynthesis at that temperature : instead of the 2.3:1 mass ratio of 60s:37s ribosomal subunits characteristic of wild type , the mutant strain pj30201 ( called crib-1 for cytoplasmic ribosome biosynthesis ) exhibits a mass ratio of approximately 7.2:1 .
C0035553
ribosome
C0010834
cytoplasmic