Specific ribonucleoprotein fragments from 40-S ribosomal subunits.

ABSTRACT

Well-defined ribonucleoprotein fragments, resulting from the action of endogenous nuclease on 40-S subunits, were able to be separated when using high concentrations of LiCl. The ribonucleoproteins obtained sedimented at 12, 17 S, 23 S and 30 S and contained 8 S, 12 S and 17 S RNA, respectively, associated with a few proteins. The proteins extracted from the fragments were [3H] labeled by reductive methylation and their molar proportion was determined. The smallest fragment (12, 17 S) contained only three proteins, S8, S9 and S24. The 23-S and 30-S materials contained some proteins in common, S15, S19, S22, S25; S16 was found mainly in 30 S. Two proteins, S26 and "protein y" were found mainly in 23 S material. Thus, these results can give information on the relative location of certain proteins in the 40-S subunits.