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Function
Increased sodium tolerance protein 1 (Ist1) is a family member of the transport-III (ESCRT-III) forming high-order helical structures with CHMP1B which are required in remodeling membranes during abscission[1].
Increased sodium tolerance protein 3 (Ist3) or U2 snRNP component IST3 (Ist3) is part of the spliceosome which is involved in transcription and pre-mRNA splicing. Ist3 interacts with human elongation factors and strongly stimulates polymerase elongation[2].
Disease
Somatic mutations in Ist3 have been found in various malignancies like breast cancer, pancreatic cancer, uveal melanoma and others[3].
Structural highlights
The structure of the yeast Ist1 N-terminal complex with ESCRT-III subunit Did2 which is part of a high-order helical structure shows 8 side chains of Ist1 pointing toward the Did2 helix. 3 residues of Ist1 were found by mutational studies to interact with Did2[4]. All Ist1/Did2 interactions.
- ↑ Bajorek M, Schubert HL, McCullough J, Langelier C, Eckert DM, Stubblefield WM, Uter NT, Myszka DG, Hill CP, Sundquist WI. Structural basis for ESCRT-III protein autoinhibition. Nat Struct Mol Biol. 2009 Jul;16(7):754-62. Epub 2009 Jun 14. PMID:19525971 doi:10.1038/nsmb.1621
- ↑ Fong YW, Zhou Q. Stimulatory effect of splicing factors on transcriptional elongation. Nature. 2001 Dec 20-27;414(6866):929-33. PMID:11780068 doi:https://dx.doi.org/10.1038/414929a
- ↑ Tanikawa M, Sanjiv K, Helleday T, Herr P, Mortusewicz O. The spliceosome U2 snRNP factors promote genome stability through distinct mechanisms; transcription of repair factors and R-loop processing. Oncogenesis. 2016 Dec 19;5(12):e280. doi: 10.1038/oncsis.2016.70. PMID:27991914 doi:https://dx.doi.org/10.1038/oncsis.2016.70
- ↑ Xiao J, Chen XW, Davies BA, Saltiel AR, Katzmann DJ, Xu Z. Structural basis of Ist1 function and Ist1-Did2 interaction in the multivesicular body pathway and cytokinesis. Mol Biol Cell. 2009 Aug;20(15):3514-24. Epub 2009 May 28. PMID:19477918 doi:10.1091/mbc.E09-05-0403
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3D structures of increased sodium tolerance protein
Updated on 18-September-2025
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- Increased sodium tolerance protein 1
- 6tza - hIst1 N-terminal (mutant) 1-193 - human - Cryo EM
- 3jc1, 6tz5, 6tz4 - hIst1 N-terminal + CHMP1B - Cryo EM
- 6e8g - hIst1 N-terminal + CHMP1B + DNA - Cryo EM
- 3ggy - yIst1 N-terminal - yeast
- 3ggz - yIst1 N-terminal + vascular protei-sorting-associted protein 46 peptide
- Increased sodium tolerance protein 2
- Increased sodium tolerance protein 3 or U2 snRNP component IST3
- 2my3 - yIst3 residues 25-138 + pre-mRNA leakage protein peptide - NMR
- 2my2, 4uqt - yIst3 residues 25-138 + pre-mRNA-splicing factor peptide - NMR
- 2my3 - yIst3 residues 25-138 + pre-mRNA leakage protein peptide + pre-mRNA-splicing factor peptide - NMR
- 5lqw, 5zwo, 5zwm, 5gm6 - yIst3 in spliceosome - Cryo EM
- 6g90, 5nrl - yIst3 in prespliceosome - Cryo EM
References
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