title: Rice OsERG3 encodes an unusual small C2-domain protein containing a Ca(2+)-binding module but lacking phospholipid-binding properties.
abstract: BACKGROUND
  The C2 domain is a Ca(2+)/phospholipid-binding motif found in many proteins involved in signal transduction or membrane trafficking. OsERG3 is a homolog of OsERG1, a gene encoding a small C2-domain protein in rice.
  
  
  METHODS
  OsERG3 Ca(2+)-binding and phospholipid-binding assays were carried out using (3)H-labeled phospholipid liposomes and a (45)Ca(2+) overlay assay, respectively. Cytosolic expression of OsERG3 was investigated by Western blot analysis and the OsERG3::smGFP transient expression assay.
  
  
  RESULTS
  OsERG3 transcript levels were greatly enhanced by treatment with a fungal elicitor and Ca(2+)-ionophore. OsERG3 protein proved unable to interact with phospholipids regardless of the presence or absence of Ca(2+) ions. Nonetheless, OsERG3 displayed calcium-binding activity in an in vitro(45)Ca(2+)-binding assay, a property not observed with OsERG1. The cytosolic location of OsERG3 was not altered by the presence of fungal elicitor or Ca(2+)-ionophore.
  
  
  CONCLUSIONS
  OsERG3 encodes a small C2-domain protein consisting of a single C2 domain. OsERG3 binds Ca(2+) ions but not phospholipids. OsERG3 is a cytosolic soluble protein. The OsERG3 gene may play a role in signaling pathway involving Ca(2+) ions.
  
  
  CONCLUSIONS
  The data demonstrate that OsERG3 is an unusual small C2-domain protein containing a Ca(2+)-binding module but lacking phospholipid-binding properties.
authors.affiliation: Division of Applied Life Sciences (BK21 Program), Gyeongsang National University, Jinju 660701, Republic of Korea.
authors.forename: Chang Ho
authors.initials: CH
authors.lastname: Kang
authors.forename: Byeong Cheol
authors.initials: BC
authors.lastname: Moon
authors.forename: Hyeong Cheol
authors.initials: HC
authors.lastname: Park
authors.forename: Seong Cheol
authors.initials: SC
authors.lastname: Koo
authors.forename: Joo Mi
authors.initials: JM
authors.lastname: Jeon
authors.forename: Yong Hwa
authors.initials: YH
authors.lastname: Cheong
authors.forename: Woo Sik
authors.initials: WS
authors.lastname: Chung
authors.forename: Chae Oh
authors.initials: CO
authors.lastname: Lim
authors.forename: Jae-Yeon
authors.initials: JY
authors.lastname: Kim
authors.forename: Byung-Dae
authors.initials: BD
authors.lastname: Yoon
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Lee
authors.forename: Cha Young
authors.initials: CY
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D012275:Oryza / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D002135:Calcium-Binding Proteins; D010743:Phospholipids; D010940:Plant Proteins; D012333:RNA, Messenger; D002118:Calcium