Protein interaction screening identifies SH 3 RF 1 as a new regulator of FAT 1 protein levels

Mutations and ectopic FAT 1 cadherin expression are implicated in a broad spectrum of diseases ranging from developmental disorders to cancer. The regulation of FAT 1 and its downstream signalling pathways remain incompletely understood. We hypothesized that identification of additional proteins interacting with the FAT 1 cytoplasmic tail would further delineate its regulation and function. A yeast two‐hybrid library screen carried out against the juxtamembrane region of the cytoplasmic tail of FAT 1 identified the E3 ubiquitin‐protein ligase SH 3 RF 1 as the most frequently recovered protein‐binding partner. Ablating SH 3 RF 1 using si RNA increased cellular FAT 1 protein levels and stabilized expression at the cell surface, while overexpression of SH 3 RF 1 reduced FAT 1 levels. We conclude that SH 3 RF 1 acts as a negative post‐translational regulator of FAT 1 levels.