| We found that the integrity of two Ser residues at positions 535 and 539 within the specific destruction motif present in the cytoplasmic tail of IFNAR 1 is essential for the ability of IFNAR 1 to recruit beta Trcp as well as to undergo efficient ubiquitination and degradation . ^^^ Expression of Tyk 2 stabilized IFNAR 1 in a manner that was dependent neither on its binding to beta Trcp nor IFNAR 1 ubiquitination . ^^^ We discuss the complexities and specifics of the ubiquitination and degradation of IFNAR 1 , which is a beta Trcp substrate that undergoes degradation via a lysosomal pathway . . ^^^ |