5dkj | pdb_00005dkj
Yeast 20S proteasome in complex with octreotide-PI
Structural highlights
FunctionPSA1_YEAST The proteasome degrades poly-ubiquitinated proteins in the cytoplasm and in the nucleus. It is essential for the regulated turnover of proteins and for the removal of misfolded proteins. The proteasome is a multicatalytic proteinase complex that is characterized by its ability to cleave peptides with Arg, Phe, Tyr, Leu, and Glu adjacent to the leaving group at neutral or slightly basic pH. It has an ATP-dependent proteolytic activity. Publication Abstract from PubMedClinical application of proteasome inhibitors (PIs) is so far limited to peripheral blood cancers due to the pronounced cytotoxicity towards all cell types. Targeted delivery of PIs could permit the treatment of other cancers along with decreasing side effects. Herein we describe the first small-molecule proteasome inhibitor conjugate for targeted delivery, created by fusing PIs to a synthetic ligand of somatostatin receptors, which are highly expressed in a variety of tumors. X-ray crystallographic studies and in vitro IC50 measurements demonstrated that addition of the cyclopeptide octreotide as a targeting vehicle does not affect the PI's binding mode. The cytotoxicity of the conjugate against somatostatin-receptor-expressing cells was up to 11-fold higher than that of a non-targeting surrogate. We have therefore established PIs as a new payload for drug conjugates and have shown that targeted delivery thereof could be a promising approach for the broader application of this FDA-approved class of compounds. Targeted Delivery of Proteasome Inhibitors to Somatostatin-Receptor-Expressing Cancer Cells by Octreotide Conjugation.,Beck P, Cui H, Hegemann JD, Marahiel MA, Kruger A, Groll M ChemMedChem. 2015 Dec;10(12):1969-73. doi: 10.1002/cmdc.201500449. Epub 2015 Oct , 16. PMID:26471124[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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