In a system of purified components , binding of __NODE__ 4 , diphosphate and a protein fragment ( 1 307 ) containing a phosphotyrosine binding domain and a pleckstrin homology ( PH ) domain from __NODE__ protein is greater than binding of __NODE__ 4 , diphosphate and a protein fragment ( 1 307 ) containing a phosphotyrosine binding domain and a mutant pleckstrin homology ( PH ) domain ( K21L K23L R28C ) from __NODE__ protein .