title: The LxxxA motif in the third transmembrane helix of the maize aquaporin ZmPIP2;5 acts as an ER export signal.
abstract: The subcellular localization of aquaporins belonging to the plasma membrane intrinsic protein (PIP) subfamily is highly regulated. In maize (Zea mays), ZmPIP1s are retained in the endoplasmic reticulum (ER) whereas ZmPIP2s are able to reach the plasma membrane (PM). We recently identified a new sorting determinant which is buried within the third transmembrane domain (TM3) of ZmPIP2;5. The Leu127 and Ala131 are required for the localization of ZmPIP2;5 in the PM and for its exit from the ER. However, when inserted into ZmPIP1;2, these amino acids were not sufficient to export the protein out of the ER. Here, we show that, when inserted into a truncated version of ZmPIP1;2 consisting only of its TM3 region, Leu127 and Ala131 of ZmPIP2;5 are able to partially bring the protein to the PM, demonstrating the active anterograde sorting function of this motif.
authors.affiliation: a Institut des Sciences de la Vie ; Université catholique de Louvain ; Louvain-la-Neuve , Belgium.
authors.forename: Adrien S
authors.initials: AS
authors.lastname: Chevalier
authors.forename: François
authors.initials: F
authors.lastname: Chaumont
mesh_terms: D020816:Amino Acid Motifs; D020346:Aquaporins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D015398:Signal Transduction; D003313:Zea mays / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D010940:Plant Proteins
keywords: Aquaporin; ER, endoplasmic reticulum; PIP, plasma membrane intrinsic protein; PM, plasma membrane; Plasma membrane intrinsic protein; Secretory Pathway; Sorting Motif; TM, transmembrane domain; Trafficking; Transmembrane Domain; Zea mays; Zm, Zea mays; mYFP, monomeric yellow fluorescent protein