title: Pinkbar is an epithelial-specific BAR domain protein that generates planar membrane structures.
abstract: Bin/amphipysin/Rvs (BAR)-domain proteins sculpt cellular membranes and have key roles in processes such as endocytosis, cell motility and morphogenesis. BAR domains are divided into three subfamilies: BAR- and F-BAR-domain proteins generate positive membrane curvature and stabilize cellular invaginations, whereas I-BAR-domain proteins induce negative curvature and stabilize protrusions. We show that a previously uncharacterized member of the I-BAR subfamily, Pinkbar, is specifically expressed in intestinal epithelial cells, where it localizes to Rab13-positive vesicles and to the plasma membrane at intercellular junctions. Notably, the BAR domain of Pinkbar does not induce membrane tubulation but promotes the formation of planar membrane sheets. Structural and mutagenesis analyses reveal that the BAR domain of Pinkbar has a relatively flat lipid-binding interface and that it assembles into sheet-like oligomers in crystals and in solution, which may explain its unique membrane-deforming activity.
authors: Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Anette
authors: A
authors: Pykäläinen
authors: Malgorzata
authors: M
authors: Boczkowska
authors: Hongxia
authors: H
authors: Zhao
authors: Juha
authors: J
authors: Saarikangas
authors: Grzegorz
authors: G
authors: Rebowski
authors: Maurice
authors: M
authors: Jansen
authors: Janne
authors: J
authors: Hakanen
authors: Essi V
authors: EV
authors: Koskela
authors: Johan
authors: J
authors: Peränen
authors: Helena
authors: H
authors: Vihinen
authors: Eija
authors: E
authors: Jokitalo
authors: Marjo
authors: M
authors: Salminen
authors: Elina
authors: E
authors: Ikonen
authors: Roberto
authors: R
authors: Dominguez
authors: Pekka
authors: P
authors: Lappalainen
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D018360:Crystallography, X-Ray; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism*; D007365:Intercellular Junctions / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000166:cytology; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008565:Membrane Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D051379:Mice; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary; D053835:Unilamellar Liposomes / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000378:metabolism
chemical_list: C567958:Baiap2l2 protein, mouse; D008565:Membrane Proteins; D053835:Unilamellar Liposomes; C484177:Rab13 protein, mouse; D020691:rab GTP-Binding Proteins