Characterization of fibroblast growth factor-2 binding to ribosomes.
We have examined the binding of FGF-2 to ribosomes and have found that in NIH 3T3 cells that synthesize high amounts of all FGF-2 forms, both 18 kDa and HMW forms of FGF-2 bind to ribosomes. Ribosomes purified from these cells were treated with RNase or puromycin to identify the binding site of FGF-2 on the ribosome. Neither RNase nor puromycin treatment affected the in vivo binding of FGF-2 to ribosomes suggesting that FGF-2 binds ribosomal protein or rRNA, but not mRNA. The stoichiometry of binding in these cells was approximately 1 FGF-2 molecule bound per 1 ribosome. Binding was unaffected by high salt treatment indicating that FGF-2 tightly associates with polysomes. An in vitro binding experiment performed with purified ribosomes and recombinant FGF-2 suggested that the binding site is saturable. HBNF, a protein with similar charge and size to FGF-2, bound 15-fold less than FGF-2 to purified ribosomes. These results indicate that the binding of FGF-2 to ribosomes is specific.
Klein
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Department of Cell Biology, Raymond and Beverly Sackler Foundation Laboratory, New York University Medical Center, New York, NY 10016, USA.
Morimoto
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T
Rifkin
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DB
D016475:3T3 Cells; D000818:Animals; D002499:Centrifugation, Density Gradient; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D051379:Mice; D012270:Ribosomes / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D013379:Substrate Specificity
D016222:Fibroblast Growth Factor 2