Two cellular proteins bind specifically to a purine-rich sequence necessary for the destabilization function of a c-fos protein-coding region determinant of mRNA instability.
The c-fos proto-oncogene mRNA is rapidly degraded within minutes after its appearance in the cytoplasm of growth factor-stimulated mammalian fibroblasts. At least two functionally independent sequence elements are responsible for the lability of c-fos mRNA. One of these determinants is located within a 0.32-kb sequence present in the protein-coding region. We demonstrate by gel mobility shift experiments and UV cross-linking that at least two protein factors specifically interact with a 56-nucleotide purine-rich sequence located at the 5' end of the 0.32-kb coding region determinant of mRNA instability (CRDI). One protein is predominantly associated with the polysomes, while the other is detected in the post-ribosomal supernatant. Sequence comparison of members of the fos gene family revealed that the high purine content of the protein-binding region is conserved through evolution. Deletion of this region from the 0.32-kb CRDI severely impedes its function as an RNA-destabilizing element. Our results suggest that binding of the two proteins to the purine-rich sequence may participate in the rapid mRNA decay mediated by this 0.32-kb c-fos CRDI.
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Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston 77030.
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D016475:3T3 Cells; D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D000090063:Proto-Oncogene Mas; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D011687:Purines / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D014466:Ultraviolet Rays
D004268:DNA-Binding Proteins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D016760:Proto-Oncogene Proteins c-fos; D011687:Purines; D012333:RNA, Messenger