Table 2.
Properties of Sequence-specific RNA-binding proteins interacting with the IGF1R 5’-UTR / IRES
| Designation | MW | Relation to IRES | Intracellular Localization | Status in Breast cell lines | Change with 3-D culture MCF-10A | Status in Breast Specimens | Inter-molecular Association | Nuclear extraction/Cytoplasmic Susceptibility | Affect of Mg++ on Affinity |
|---|---|---|---|---|---|---|---|---|---|
| Band 1 series | ~125-250 kDa | External ITAFs | Cytoplasmic | Lost upon acinar differ. | serine phosph. | susceptible to MNase in cytoplasm | favored by ↑ Mg++ (↑RNA structure) | ||
| Band 2 | ~105 kDa | Internal ITAF | Nuclear | T47D>MCF-10A | Lost upon acinar differ. | positive 3 / 3 breast metastases | hnRNP | favored by ↓ Mg++ | |
| Band 3 | ~95 kDa | Internal ITAF | Nuclear | MCF-10A>T47D | Lost upon microdialysis | ||||
| Band 4 | ~85kDa | Internal ITAF | Cyto/Nucl | MCF-10A>T47D (inverse corr. IRES activity) | Selectively retained upon acinar differ. | positive 3 / 3 breast metastases | Ribosomal salt wash | favored by ↓ Mg++ | |
| Band 4b | ~75kDa | Internal ITAF | Nuclear | T47D>MCF-10A | highly active 1/3 metastases 2/3 1° tumors (corr. w/ poor diff) | hnRNP | recovery ↑ by 1M NaCl, DOC or nuclease | ||
| Band 5 | ~70 kDa | Internal ITAF | Cyt>Nuc | T47D>MCF-10A | active in 3/3 metastases 2/3 1° tumors (corr. malignant phenotype) | Tightly associated Ribosomes | susceptible to MNase in cytoplasm | favored by ↓ Mg++ | |
| Band 6 series | ~60 kDa | Internal ITAFs | Cyto / Nucl | active in 2/3 metastases 2/3 1° tumors | highly labile | susceptible to high salt in cytoplasm | |||
| Band 7 | ~ 50 kDa | External ITAF | Nuc>Cyt | T47D>MCF-10A | Lost upon acinar diff. | highly active 1/3 metastases 1/3 1° tumors (corr. w/ poor diff) | favored by ↑ Mg++ (↑ RNA structure) | ||
| Band 8a | ~45 kDa | Internal ITAF | Cyto / Nucl | Lost upon acinar diff. | recovery ↑ by 1M NaCl, DOC or nuclease | ||||
| Band 8d (hnRNP C) | 42 kDa | Internal ITAF | Nuc>Cyt | active in 3/3 metastases | hnRNP | susceptible to high salt in cytoplasm | |||
| Band 9 | ~37 kDa | External ITAF | Nuc>Cyt | Retained | readily detectable | serine phosph; asso Ribosomes | favored by ↑ Mg++ | ||
| Band 10 | ~25 kDa | External ITAF | Cyto / Nucl | readily detectable | asso Ribosomes | recovery ↑ by high salt |