FIGURE 8:

Model of Art1 regulation. (A) Art1 schematic showing the conserved regions predicted to form the arrestin fold (colored), and the loop and tail regions (gray). (B) Cartoon depicting the predicted organization of the conserved arrestin fold and the localization of the loops. (C) Summary of the effects of Art1 loop region deletions. (D) New modes of Art1 regulation. In addition to the previously identified regulation through Npr1 or Ppz1/2, Art1 phosphorylation/dephosphorylation reactions can be mediated by Clg1-Pho85 and Pho80-Pho85 to regulate its activity. Phosphorylation of Art1 loops and the C-tail regulate its function by affecting its PM localization. When phosphorylated on loop 1, the “miniloop,” and the C-tail, Art1 remains in the cytosol or associated with the Golgi, rendering it inactive. Upon dephosphorylation, Art1 can associate with the PM, where it can recognize its substrate cargoes resulting in ubiquitylation and endocytosis.