In a system of purified components , binding of a monoubiquitinated phosphorylated ( S33 S37 ) protein fragment ( 19 44 ) from __SP__ __NODE__ protein and a protein protein complex consisting of mutant __SP__ __NODE__ ( N terminal truncation 1 138 ) and of mutant __SP__ Skp1 ( deletion 38 43 71 82 ) is the same as binding of a monoubiquitinated phosphorylated ( S33 S37 ) protein fragment ( 19 44 ) from mutant __SP__ __NODE__ protein ( deletion 21 24 ) and a protein protein complex consisting of mutant __SP__ __NODE__ ( N terminal truncation 1 138 ) and of mutant __SP__ Skp1 ( deletion 38 43 71 82 ) .