Interleukin-10 (IL-10) initiates potent anti-inflammatory effects via activating its cell surface receptor, composed of IL-10R1 and IL-10R2 subunits.The level of IL-10R1 is a major determinant of the cellular signaling sensitivity to IL-10.Here, via a series of biochemical analyses using 293T cells reconstituted with IL-10R1, we identify the latter as a novel substrate of βTrCP-containing ubiquitin E3 ligase.Efficient βTrCP binding to IL-10R1 requires phosphorylation of a canonical (318DSGFGS) and a slightly deviated (369DSGICLQEP) βTrCP recognition motif located on the intracellular tail of the receptor, with both motifs exhibiting high levels of conservation in mammals..βTrCP recruitment leads to ubiquitination, degradation and down-regulation of IL-10R1, subsequently reducing the cellular responses to IL-10.Our study uncovers a novel negative regulatory mechanism that may potentially affect IL-10 function in target cells under physiological or pathological conditions.