title: Molecular cloning, phylogenetic analysis, and expression profiling of endoplasmic reticulum molecular chaperone BiP genes from bread wheat (Triticum aestivum L.).
abstract: BACKGROUND
  The endoplasmic reticulum chaperone binding protein (BiP) is an important functional protein, which is involved in protein synthesis, folding assembly, and secretion. In order to study the role of BiP in the process of wheat seed development, we cloned three BiP homologous cDNA sequences in bread wheat (Triticum aestivum), completed by rapid amplification of cDNA ends (RACE), and examined the expression of wheat BiP in wheat tissues, particularly the relationship between BiP expression and the subunit types of HMW-GS using near-isogenic lines (NILs) of HMW-GS silencing, and under abiotic stress.
  
  
  RESULTS
  Sequence analysis demonstrated that all BiPs contained three highly conserved domains present in plants, animals, and microorganisms, indicating their evolutionary conservation among different biological species. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) revealed that TaBiP (Triticum aestivum BiP) expression was not organ-specific, but was predominantly localized to seed endosperm. Furthermore, immunolocalization confirmed that TaBiP was primarily located within the protein bodies (PBs) in wheat endosperm. Three TaBiP genes exhibited significantly down-regulated expression following high molecular weight-glutenin subunit (HMW-GS) silencing. Drought stress induced significantly up-regulated expression of TaBiPs in wheat roots, leaves, and developing grains.
  
  
  CONCLUSIONS
  The high conservation of BiP sequences suggests that BiP plays the same role, or has common mechanisms, in the folding and assembly of nascent polypeptides and protein synthesis across species. The expression of TaBiPs in different wheat tissue and under abiotic stress indicated that TaBiP is most abundant in tissues with high secretory activity and with high proportions of cells undergoing division, and that the expression level of BiP is associated with the subunit types of HMW-GS and synthesis. The expression of TaBiPs is developmentally regulated during seed development and early seedling growth, and under various abiotic stresses.
authors.forename: Jiantang
authors.initials: J
authors.lastname: Zhu
authors.forename: Pengchao
authors.initials: P
authors.lastname: Hao
authors.forename: Guanxing
authors.initials: G
authors.lastname: Chen
authors.forename: Caixia
authors.initials: C
authors.lastname: Han
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Li
authors.forename: Friedrich J
authors.initials: FJ
authors.lastname: Zeller
authors.forename: Sai L K
authors.initials: SL
authors.lastname: Hsam
authors.forename: Yingkao
authors.initials: Y
authors.lastname: Hu
authors.forename: Yueming
authors.initials: Y
authors.lastname: Yan
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D055864:Droughts; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D020869:Gene Expression Profiling; D005983:Glutens / Q000032:analysis / Q000302:isolation & purification; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009928:Organ Specificity; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000502:physiology; D017434:Protein Structure, Tertiary; D036226:Seedlings / Q000235:genetics / Q000502:physiology; D012639:Seeds / Q000235:genetics / Q000502:physiology; D016415:Sequence Alignment; D013312:Stress, Physiological; D014908:Triticum / Q000235:genetics* / Q000502:physiology
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D005983:Glutens; C037302:glutenin