| Using the yeast two hybrid system , we have identified a novel beta arrestin 1 binding protein , NSF ( N ethylmaleimide sensitive fusion protein ) , an ATPase essential for many intracellular transport reactions . ^^^ Identification of NSF as a beta arrestin 1 binding protein . ^^^ We demonstrate that purified recombinant beta arrestin 1 and NSF interact in vitro and that these proteins can be coimmunoprecipitated from cells . beta Arrestin 1 NSF complex formation exhibits a conformational dependence with beta arrestin 1 preferentially interacting with the ATP bound form of NSF . ^^^ In contrast to the beta arrestin 1 clathrin interaction , however , the phosphorylation state of beta arrestin 1 does not affect NSF binding . ^^^ Furthermore , when coexpressed with a beta arrestin 1 mutant ( betaarr1S412D ) that mimics a constitutively phosphorylated form of beta arrestin 1 and that acts as a dominant negative with regards to beta 2 AR internalization , NSF rescues the betaarr1S412D mediated inhibition of beta 2 AR internalization . ^^^ |