title: Intracellular auxin transport in pollen: PIN8, PIN5 and PILS5.
abstract: Cellular auxin homeostasis is controlled at many levels that include auxin biosynthesis, auxin metabolism, and auxin transport. In addition to intercellular auxin transport, auxin homeostasis is modulated by auxin flow through the endoplasmic reticulum (ER). PIN5, a member of the auxin efflux facilitators PIN protein family, was the first protein to be characterized as an intracellular auxin transporter. We demonstrated that PIN8, the closest member of the PIN family to PIN5, represents another ER-residing auxin transporter. PIN8 is specifically expressed in the male gametophyte and is located in the ER. By combining genetic, physiological, cellular and biochemical data we demonstrated a role for PIN8 in intracellular auxin homeostasis. Although our investigation shed light on intracellular auxin transport in pollen, the physiological function of PIN8 still remains to be elucidated. Here we discuss our data taking in consideration other recent findings.
authors.affiliation: Institute of Biology II/Molecular Plant Physiology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, Freiburg, Germany. cristina.dal.bosco@biologie-uni-freiburg.de
authors.forename: Cristina
authors.initials: C
authors.lastname: Dal Bosco
authors.forename: Alexander
authors.initials: A
authors.lastname: Dovzhenko
authors.forename: Klaus
authors.initials: K
authors.lastname: Palme
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000235:genetics / Q000502:physiology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D011058:Pollen / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C541719:PIN-FORMED 5 protein, Arabidopsis; C581622:PIN8 protein, Arabidopsis