1. Regulation of Iron Uptake by IRT1: Endocytosis Pulls the Trigger
Enric Zelazny, Grégory Vert 
Molecular Plant 
Volume 8, Issue 7, Pages (July 2015)
DOI: /j.molp
Copyright © 2015 The Author Terms and Conditions

2. Figure 1
Model for the Dual Regulation of IRT1 at the Transcriptional and Post-translational Levels by Metals.
(A) IRT1 promoter is not active in iron-replete conditions.
(B) Iron deficiency triggers transcriptional activation of IRT1 leading to IRT1 mRNA and IRT1 protein accumulation. In the absence of non-iron metal substrates of IRT1 (i.e. Zn, Mn, and Co), IRT1 protein is found at the outer plasma membrane domain and takes up ferrous iron.
(C) The presence of secondary metal substrates of IRT1 initiates its ubiquitination, likely in an IDF1-dependent manner, and leads to internalization of IRT1 to prevent overaccumulation of potentially toxic non-iron metals. Endosomal sorting of ubiquitinated IRT1 involves the late endosome-recruited ESCRT subunit FYVE1/FREE1. Recycling of IRT1 requires the presence of SNX1 and presumably deubiquitination.
(D) Interference with IRT1 ubiquitination triggers IRT1 accumulation at the cell surface and yields uncontrolled non-iron metal uptake leading to plant death.
ER, endoplasmic reticulum; GA, Golgi apparatus; MVB, multivesicular body; N, nucleus; PM, plasma membrane; TGN/EE, trans-Golgi network/early endosome; V, vacuole.
Molecular Plant 2015 8, DOI: ( /j.molp )
Copyright © 2015 The Author Terms and Conditions