The C-terminus of MIP-T3 protein is required for ubiquitin–proteasome-mediated degradation in human cells

The intraflagellar transport (IFT) complex is essential for the formation and functional maintenance of eukaryotic cilia which play a vital role in development and tissue homeostasis. However, the biochemical characteristics and precise functions of IFT proteins remain unknown. Here, we report that MIP-T3, a human microtubule-interacting protein recently identified as a novel conserved component of the IFT complex, is an easily degradable protein in human cell lines. Protein degradation is mediated by the ubiquitin–proteasome system, and the C-terminus is required for ubiquitination and proteasome-mediated degradation of MIP-T3 protein. This study provides the first evidence for regulation of IFT protein stability.

► In this study we examine the protein stability of MIP-T3, a novel IFT protein, in human cells.
► We found that endogenously, or ectopically expressed MIP-T3 protein is unstable.
► Protein degradation is mediated by the ubiquitin–proteasome system.
► The C-terminus is required for its ubiquitination and proteasome-mediated protein degradation.
► We provide the first evidence for regulation of IFT protein stability.