title: Plant immunophilins: a review of their structure-function relationship.
abstract: BACKGROUND
  Originally discovered as receptors for immunosuppressive drugs, immunophilins consist of two major groups, FK506 binding proteins (FKBPs) and cyclosporin A binding proteins (cyclophilins, CYPs). Many members in both FKBP and CYP families are peptidyl prolyl isomerases that are involved in protein folding processes, though they share little sequence homology. It is not surprising to find immunophilins in all organisms examined so far, including viruses, bacteria, fungi, plants and animals, as protein folding represents a common process in all living systems.
  
  
  METHODS
  Studies on plant immunophilins have revealed new functions beyond protein folding and new structural properties beyond that of typical PPIases. This review focuses on the structural and functional diversity of plant FKBPs and CYPs.
  
  
  CONCLUSIONS
  The differences in sequence, structure as well as subcellular localization, have added on to the diversity of this family of molecular chaperones. In particular, the large number of immunophilins present in the thylakoid lumen of the photosynthetic organelle, promises to deliver insights into the regulation of photosynthesis, a unique feature of plant systems. However, very little structural information and functional data are available for plant immunophilins.
  
  
  CONCLUSIONS
  Studies on the structure and function of plant immunophilins are important in understanding their role in plant biology. By reviewing the structural and functional properties of some immunophilins that represent the emerging area of research in plant biology, we hope to increase the interest of researchers in pursuing further research in this area. This article is part of a Special Issue entitled Proline-directed Foldases: Cell Signaling Catalysts and Drug Targets.
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore 117543; Institute of Life Sciences, Bhubaneswar, Orissa 751023, India.
authors.forename: Dileep
authors.initials: D
authors.lastname: Vasudevan
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore 117543.
authors.forename: Gayathri
authors.initials: G
authors.lastname: Gopalan
authors.affiliation: Institute of Life Sciences, Bhubaneswar, Orissa 751023, India.
authors.forename: Ashish
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, CA 94720, USA.
authors.forename: Veder J
authors.initials: VJ
authors.lastname: Garcia
authors.affiliation: Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, CA 94720, USA. Electronic address: sluan@berkeley.edu.
authors.forename: Sheng
authors.initials: S
authors.lastname: Luan
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore 117543. Electronic address: dbsks@nus.edu.sg.
authors.forename: Kunchithapadam
authors.initials: K
authors.lastname: Swaminathan
mesh_terms: D021983:Cyclophilins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010944:Plants / Q000201:enzymology* / Q000235:genetics; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D022021:Tacrolimus Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D021983:Cyclophilins; D022021:Tacrolimus Binding Proteins
keywords: Cyclophilin; Cyclosporin; FK506; FKBP; Immunophilin; Redox