title: Double labelling of subcellular structures with organelle-targeted GFP mutants in vivo.
abstract: BACKGROUND
  The green fluorescent protein (GFP) of Aequorea victoria is emerging as a unique tool for monitoring complex phenomena such as gene expression and organelle structure and dynamics in living cells. The recent description of GFP mutants with modified spectral properties opens numerous new applications in cell biology. However, the expression and the characteristics of these GFP mutants in living eukaryotic cells have not been verified yet.
  
  
  RESULTS
  Here, we demonstrate the usefulness of the GFP mutants for cell biology studies in vivo, by the use of wild-type GFP, a 'bright' GFP mutant (S65T) and a mutant with blue-shifted excitation and emission spectra (Y66H/Y145F). We have constructed two GFP chimeras targeted to mitochondria, mtGFP(S65T) and mtGFP(Y66H/Y145F), with the same strategy used previously for mtGFP. In addition, two GFP chimeras targeted to the nucleus, nuGFP and nuGFP(S65T), were constructed by fusing the wild-type GFP or the (S65T) mutant to the rat glucocorticoid receptor. By co-transfecting mtGFP(Y66H/Y145F) and nuGFP, the nucleus and the mitochondria were visualized simultaneously in living cells. Similarly, mtGFP and mtGFP(Y66H/Y145F) were transfected into different populations of cells, and the events of cellular fusion, and mitochondrial intermixing and/or fusion, were directly monitored.
  
  
  CONCLUSIONS
  The successful expression of organelle-targeted GFP mutants in live eukaryotes expands the uses of this fluorescent protein in cell biology, allowing direct access to key biological issues, such as the study of the interactions of different organelles in vivo. These results also open the way to other exciting applications, such as the direct study of protein redistribution and protein-protein interactions in living cells.
authors.affiliation: Department of Biomedical Sciences, University of Padova, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Rizzuto
authors.forename: M
authors.initials: M
authors.lastname: Brini
authors.forename: F
authors.initials: F
authors.lastname: De Giorgi
authors.forename: R
authors.initials: R
authors.lastname: Rossi
authors.forename: R
authors.initials: R
authors.lastname: Heim
authors.forename: R Y
authors.initials: RY
authors.lastname: Tsien
authors.forename: T
authors.initials: T
authors.lastname: Pozzan
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D003116:Color; D017931:DNA Primers; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D015388:Organelles / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D017931:DNA Primers; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins