title: A single fixation protocol for proteome-wide immunofluorescence localization studies.
abstract: Immunofluorescence microscopy is a valuable tool for analyzing protein expression and localization at a subcellular level thus providing information regarding protein function, interaction partners and its role in cellular processes. When performing sample fixation, parameters such as difference in accessibility of proteins present in various cellular compartments as well as the chemical composition of the protein to be studied, needs to be taken into account. However, in systematic and proteome-wide efforts, a need exists for standard fixation protocol(s) that works well for the majority of all proteins independent of subcellular localization. Here, we report on a study with the goal to find a standardized protocol based on the analysis of 18 human proteins localized in 11 different organelles and subcellular structures. Six fixation protocols were tested based on either dehydration by alcohols (methanol, ethanol or iso-propanol) or cross-linking by paraformaldehyde followed by detergent permeabilization (Triton X-100 or saponin) in three human cell lines. Our results show that cross-linking is essential for proteome-wide localization studies and that cross-linking using paraformaldehyde followed by Triton X-100 permeabilization successfully can be used as a single fixation protocol for systematic studies.
authors.affiliation: School of Biotechnology, AlbaNova University Center, Royal Institute of Technology (KTH), SE-106 91 Stockholm, Sweden.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Stadler
authors.forename: Marie
authors.initials: M
authors.lastname: Skogs
authors.forename: Hjalmar
authors.initials: H
authors.lastname: Brismar
authors.forename: Mathias
authors.initials: M
authors.lastname: Uhlén
authors.forename: Emma
authors.initials: E
authors.lastname: Lundberg
mesh_terms: D045744:Cell Line, Tumor; D003599:Cytoskeleton / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005557:Formaldehyde / Q000737:chemistry; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D008856:Microscopy, Fluorescence / Q000379:methods*; D008928:Mitochondria / Q000378:metabolism; D017830:Octoxynol / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D020543:Proteome; D040901:Proteomics / Q000379:methods*; D054789:Ribosome Inactivating Proteins, Type 1 / Q000494:pharmacology; D000076985:Saporins
chemical_list: D003902:Detergents; D011108:Polymers; D020543:Proteome; D054789:Ribosome Inactivating Proteins, Type 1; D005557:Formaldehyde; D017830:Octoxynol; D000076985:Saporins; D010447:Peptide Hydrolases; C003043:paraform