1979 Volume 86 Issue 3 Pages 597-603
The proteins of rat liver 40 S ribosomal subunits that interact with poly(U) were studied by the use of ATA and PDM, which are known to interact and cross-link, respectively, with ribosomal proteins.
(1) When rat liver 40 S ribosomal subunits were incubated with ATA at concentrations higher than 10-5M, their poly(U)-binding activity decreased, the decrease depending on the concentration of ATA. When 40 S subunits were incubated with various concentrations of ATA from 10-5 M to 10-3 M, two-dimensional electrophoresis of the ribosomal proteins showed that stained spots of several ribosomal roteins, S1, S6, S7, S9, S10, S23, and S24, became smaller and fainter, and finally disappeared, as the ATA concentration increased. It was found that preincubation of 40 S subunits with poly(U) almost completely prevented the disappearance of S7 and S10 proteins on treatment with 10-4 M ATA.
(2) When 40 S subunits were incubated with PDM at concentrations higher than 0.05mM, the poly(U)-binding activity showed a PDM concentration-dependent decrease of up to about 50% of the control in the case of 0.4mM PDM. When 40 S subunits were incubated with 0.4mM PDM, the protein spots S7, S9, S10, S22, S23, and S24 became smaller and fainter than the corresponding spots of non-treated 40 S subunits. On preincubation of 40 S sub-units with poly(U), distinct spots of S7 and S22 were recovered on the two-dimensional gel even after incubation with 0.4mM PDM.
Based on these results it seems probable that S7 protein is the poly(U)-interacting protein.
