Ribosomal Proteins cross‐Linked to 28‐S and 18‐S rRNA Separated by Sedimentation After Ultraviolet Irradiation of Rat‐Liver Ribosomes

Open Access
Publisher Website
Google Scholar
Abstract
Rat liver 80‐S ribosomes, irradiated with 254nm ultraviolet light for 15–60 min (0.63–2.5*105 quanta/ribosome), were treated with sodium dodecyl sulfate; 18‐S and 28‐S RNA fractions were isolated by sucrose density‐gradient centrifugation. The protein moieties of the 18‐S and 28‐S rRna fraction were labeled with 125I. After digestion of the rRNA fractions with RNase A and T1, the cross‐linked proteins were analyzed by two‐dimensional acrylamide gel electrophoresis and then autoradiography. Cross‐linkid proteins were examined further by didecyl sulfate/adcurylamide gel electrohphoresis of individual radioactive spots of proteins and their proteolytic peptides on two‐dimensional gels. The results showed that S2 and S15 were cross‐linked to 18‐SrRNA, and L5, L6 and L8 to 28‐S rRNA. Similar resulys were obtained when isolated 40‐S or 60‐S subunits were irradiated.