Ramagopal S, Davis B D
Proc Natl Acad Sci U S A. 1974 Mar;71(3):820-4. doi: 10.1073/pnas.71.3.820.
The "stringent" protein of the ribosome, required for its synthesis of (p)ppGpp, is readily lost during zonal centrifugation. However, enough can be retained to permit its qualitative localization. It is found in native 50S subunits, runoff 70S ribosomes, and polysomes, but not in native 30S subunits. This protein, therefore, appears to be attached to the 50S moiety of the ribosome, and it may be a constant (though easily removed) component of that structure rather than a factor that joins and leaves during the ribosome cycle.
核糖体合成（p）ppGpp所需的“严格”蛋白在区带离心过程中很容易丢失。然而，仍可保留足够的量以进行其定性定位。在天然50S亚基、延伸的70S核糖体和多核糖体中可发现该蛋白，但在天然30S亚基中未发现。因此，这种蛋白似乎附着于核糖体的50S部分，它可能是该结构的一个恒定（尽管容易去除）成分，而不是在核糖体循环过程中结合和离开的一个因子。
