Fig. S8.

Glutamic acid exchange mutations of PIN1 phosphosites do not result in protein kinase-independent auxin transport activation. (A) Auxin (indole-3-acetic acid, IAA) transport rates of Xenopus oocytes injected with PIN1 or PIN1 variants where S (serine) phosphosites had been replaced by possibly phosphorylation-mimicking E (glutamic acid) residues, together with protein kinases or a mock control injection as specified in the legend. (B) Immunoblot analysis of Xenopus oocytes injected with PIN1 variants and protein kinases (or mock) as specified. (Upper) Membrane fraction; (Lower) immunoblots of proteins following surface biotinylation demonstrating the presence of equal amounts of PIN1 in the plasma membrane of all oocytes.