Investigating functional roles of the amphipathic motifs of the Arf family proteins

Abstract

It is well known that the localizations of Arf family proteins are determined by their corresponding guanine nucleotide exchange factors (GEFs). But even though the GEFs can interact with the switch domains of Arf proteins, the amphipathic motifs at the N terminus of Arf proteins are also important for their specific intracellular localizations. Here, we analyzed the functional roles of the amphipathic motifs of the Golgi-localized Arf proteins, Arfrp1, the endoplasmic reticulum-localized Arf protein, Sar1A and the endosome- and plasma membrane-localized Arf protein, Arl14. We found that deleting the amphipathic helix of all of these selected Arf proteins causes dispersal of these Arf proteins from membranes, suggesting that the amphipathic helixes of these Arf proteins are vital to their localizations. In addition, we found that the amphipathic helix of Arfrp1, Arl14 or Sar1A is sufficient to bring cytosolic proteins to the Golgi, the endosomes or the ER respectively. The spatial determination mediated by Arfrp1 helix and Arl14 helix requires the acetylation modification on Arfrp1 helix and the myristoylation modification on Arl14 helix. Furthermore, we found that Annexin A2 interacts with Arl14 and contributes to the localization of Arl14. In sum, our results demonstrate the amphipathic motifs of Arfrp1, Arl14 and Sar1A are required and sufficient for determining specific intracellular localizations.

Date of Award	2018
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology