| These results suggest that 1 ) Rab 4 interacts with syntaxin 4 in a direct and specific manner , and 2 ) the interaction is regulated by the guanine nucleotide status of Rab 4 as well as by the conformational status of syntaxin 4 . . 0.71060329^^^ Although insulin stimulated [ gamma ( 32 ) P ] GTP binding to Rab 4 in a time dependent fashion , its effect on the Rab 4 interaction with syntaxin 4 was apparently biphasic ; an initial increase in Rab 4 associated with syntaxin 4 was followed by a gradual dissociation of the GTPase from syntaxin 4 . 0.56613048^^^ Direct interaction of Rab 4 with syntaxin 4 . 0.52717346^^^ |