FBXO40

Substrate-recognition component of the SCF (SKP1-CUL1-F-box protein)-type E3 ubiquitin ligase complex. Acts as a muscle-specific negative regulator of IGF1 signaling. Mechanistically, promotes polyubiquitination of IRS1 following its IGF1R-induced tyrosine phosphorylation, leading to IRS1 proteasomal degradation and attenuation of the IRS1/PI3K/AKT pathway in differentiated skeletal muscle. Also mediates IRS1 degradation downstream of STAT3 activation in the context of inflammatory insulin resistance..

Function from UniProtKB (Q9UH90), read 2026-09-23. CC BY 4.0.