PYR-41

PYR-41 is a selective and cell permeable inhibitor of ubiquitin-activating enzyme E1 with an IC₅₀ of < 10 μM, with little activity at E2 and E3. IC50 & Target: IC50: < 10 μM (E1) In Vitro: PYR-41 increases total sumoylation in cells in addition to blocking ubiquitylation. PYR-41 attenuates cytokine-mediated nuclear factor-κB activation. PYR-41 also prevents the downstream ubiquitylation and proteasomal degradation of IκBα. Furthermore, PYR-41 inhibits degradation of p53 and activates the transcriptional activity of this tumor suppressor^[1]. PYR-41 (50?μM) promotes accumulation of ubiquitinated proteins. PYR-41 causes a concentration-dependent (10-50 μM) decline in DUB activity in Z138 cells after 4 h. PYR-41 potently inhibits USP5 DUB activity, even at the lowest concentration (10 μM). PYR-41 potently (10-50 μM) inhibits the activity of various DUBs, determined to represent USP9x, USP5, USP14, UCH37 and UCH-L3. Co-treatment of Z138 cells with DTT and PYR-41 completely abolishes the accumulation of ubiquitinated proteins^[2].