The cis-acting elements involved in endonucleolytic cleavage of the 3' UTR of human IGF-II mRNAs bind a 50 kDa protein.
Site-specific cleavage of human insulin-like growth factor II mRNAs requires two cis-acting elements, I and II, that are both located in the 3' untranslated region and separated by almost 2 kb. These elements can interact and form a stable RNA-RNA stem structure. In this study we have initiated the investigation of transacting factors involved in the cleavage of IGF-II mRNAs. The products of the cleavage reaction accumulate in the cytoplasm, suggesting that cleavage occurs in this cellular compartment. By electrophoretic mobility shift assays, we have identified a cytoplasmic protein with an apparent molecular weight of 48-50 kDa, IGF-II cleavage unit binding protein (ICU-BP), that binds to the stem structure formed by interaction of parts of the cis-acting elements I and II. The binding is resistant to high K+ concentrations and is dependent on Mg2+. In addition, ICU-BP binding is dependent on the cell density and correlates inversely with the IGM-II mRNA levels. In vivo cross-linking data show that this protein is associated with IGF-II mRNAs in vivo.
Scheper
W
W
Laboratory for Physiological Chemistry, Graduate School of Developmental Biology, Ultrecht University, The Netherlands.
Holthuizen
P E
PE
Sussenbach
J S
JS
D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D015342:DNA Probes / Q000235:genetics; D004720:Endonucleases / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*
D015342:DNA Probes; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D007335:Insulin-Like Growth Factor II; D004720:Endonucleases