A novel 5S RNA-protein (RNP) complex in human and mouse cells has been analyzed using patient autoantibodies. The RNP is small (approximately 7S) and contains most of the nonribosome-associated 5S RNA molecules in HeLa cells. The 5S RNA in the particle is matured at its 3' end, consistent with the results of in vivo pulse-chase experiments which indicate that this RNP represents a later step in 5S biogenesis than a previously described 5S*/La protein complex. The protein moiety of the 5S RNP has been identified as ribosomal protein L5, which is known to be released from ribosomes in a complex with 5S after various treatments of the 60S subunit. Indirect immunofluorescence indicates that the L5/5S complex is concentrated in the nucleolus. L5 may therefore play a role in delivering 5S rRNA to the nucleolus for assembly into ribosomes.
A 5S rRNA/L5 complex is a precursor to ribosome assembly in mammalian cells.
J A Steitz, C Berg, J P Hendrick, H La Branche-Chabot, A Metspalu, J Rinke, T Yario; A 5S rRNA/L5 complex is a precursor to ribosome assembly in mammalian cells.. J Cell Biol 1 March 1988; 106 (3): 545–556. doi: https://doi.org/10.1083/jcb.106.3.545
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