| On the other hand , the PDZ domain of PICK 1 is capable of interacting with constitutively active , GTP bound forms of ARF 1 and ARF 3 , but neither with those of ARF5 / 6 nor with the GDP bound ARFs . ^^^ The PICK 1 ARF interaction is abrogated by introduction of mutations in the PDZ domain or by deletion of the extreme C terminus of ARF 1 . ^^^ |