JBC, Vol. 250, Issue 4, 1311-1318, Feb, 1975
Evidence for heterogeneity of ribosomes within the HeLa cell
E. H. McConkey and E. J. Hauber
The proteins of several subsets of ribosomal subunits isolated from HeLa
cells were separated by high resolution electrophoresis in polyacrylamide
slab gels containing sodium dodecyl sulfate. Comparisons were made among
native subunits, and subunits derived from single ribosomes, free
polysomes, and membrane-bound polysomes. At least 10 heterogeneously
distributed proteins were identified among the 40 S subunit proteins,
compared wtih 17 to 20 proteins that occurred in all 40 S subunit classes.
All 60 S subunits shared 34 separable proteins. One protein was missing
only from membrane-bound 60 S subunits and another protein was present only
in membrane-bound 60 S subunits. It is suggested that these two proteins
regulate the binding of 60 S subunits to the endoplasmic reticulum.