A novel and highly efficient two-step affinity chromatography protocol has been developed and is described in detail. The method is based on a small purification tag with two inherent affinities and is applicable to a wide range of target proteins with different properties.
Recently developed imaging techniques using near-infrared fluorescence (NIRF) may help elucidate the role the lymphatic system plays in cancer metastasis, immune response, wound repair, and other lymphatic-associated diseases.
Here we describe an optimized technique to produce high-quality vitamin A/RBP complex and two real-time monitoring techniques to study vitamin A transport by STRA6, the RBP receptor.
Xenopus embryonic epithelia are an ideal model system to study cell behaviors such as polarity development and shape change during epithelial morphogenesis. Traditional histology of fixed samples is increasingly being complemented by live-cell confocal imaging. Here we demonstrate methods to isolate frog tissues and visualize live epithelial cells and their cytoskeleton using live-cell confocal microscopy.
We are presenting an in vivo assay to test blood vessel permeability. This assay is based on intravenous injection of a dye and subsequent visualization of its diffusion into interstitial spaces.
A method to measure the persistence length or flexural rigidity of biopolymers is described. The method uses a kinesin-driven microtubule gliding assay to experimentally determine the persistence length of individual microtubules and is adaptable to actin-based gliding assays.
Blood-brain barrier disruption aids the delivery of certain drugs to the brain. Mannitol delivered intra-arterially shrinks cells surrounding blood vessels in order to physically disrupt the barrier.
An efficient procedure to assess the oligomerization propensity of single-pass transmembrane domains (TMDs) is described. Chimeric proteins consisting of the TMD fused to ToxR are expressed in an E. coli reporter strain. TMD-induced oligomerization causes dimerization of ToxR, activation of transcription and production of the reporter protein, -galactosidase.
Quantifying Glomerular Permeability of Fluorescent Macromolecules Using 2-Photon Microscopy in Munich Wistar Rats
A technique utilizing high resolution intavital 2-photon microscopy to directly visualize and quantify gloemrular filtration in surface glomeruli. This method allows for direct determination of permeability characteristics of macromolecules in both normal and diseased states.
Department of Medicine, St. Luke's Roosevelt Medical Center
Transgenic mice or viral vectors have been used to increase protein expression within the lung. However, these techniques are time-consuming, technically challenging and have off-target effects that can confound results. Our protein transfection protocol uses a lipid based transfection reagent and an ultrafine microsprayer to uniformly deliver active protein to lung cells.
1Department of Biochemistry and Molecular Genetics, University of Illinois Chicago - UIC, 2Research Unit on Biomedical Informatics, Universitat Pompeu Fabra, 3Genome Technology Core, Whitehead Institute for Biomedical Research
Here we are presenting a chromatin immunoprecipitation (ChIP) procedure for genome-wide location analysis of protein isoforms that differ in a histone-binding domain. We are applying it to ChIP-Seq analysis to identify the targets of the KDM5A/JARID1A/RBP2 histone demethylase.
In ovo Electroporation in Chick Midbrain for Studying Gene Function in Dopaminergic Neuron Development
1Northwestern University Feinberg School of Medicine, Children's Hospital of Chicago Research Center, 2Departments of Pediatrics, Neurology and Physiology, Northwestern University Feinberg School of Medicine
To assess the function and the regulation of genes during the development of midbrain dopaminergic neurons, we describe a method that involves in ovo electroporation of plasmid DNA constructs into embryonic chick ventral midbrain dopaminergic neuron progenitors. This technique can be used to achieve efficient expression of genes of interest to study different aspects of midbrain development and dopaminergic neuron differentiation.
Lipid Vesicle-mediated Affinity Chromatography using Magnetic Activated Cell Sorting (LIMACS): a Novel Method to Analyze Protein-lipid Interaction
To test the interaction of a protein with its target lipid we used MACS and Annexin V-conjugated magnetic beads and lipid vesicles synthesized from the target lipid and Annexin V-binding phosphatidylserine. Proteins bound to the target lipid are co-purified and analyzed after elution from the beads.
Proteins bind to filamentous actin (F-actin) through distinct actin binding modules. In this video we demonstrate the procedure of actin co-sedimentation, which is an in vitro assay routinely used to analyze proteins or specific domains that bind F-actin.
The subcellular localization of proteins is important in determining the spatio-temporal regulation of cell signaling. Here, we describe bimolecular fluorescence complementation (BiFC) as a straightforward method for monitoring the spatial interactions of proteins in the cell.
Crystal structure of protein–DNA complexes can provide insight into protein function, mechanism, as well as, the nature of the specific interaction. Here, we report how to optimize the length, sequence and ends of duplex DNA for co-crystallization with Escherichia coli SeqA, a negative regulator of replication initiation.
Guidelines for computer based structural and functional characterization of protein using the I-TASSER pipeline is described. Starting from query protein sequence, 3D models are generated using multiple threading alignments and iterative structural assembly simulations. Functional inferences are thereafter drawn based on matches to proteins with known structure and functions.
Concurrent Quantitative Conductivity and Mechanical Properties Measurements of Organic Photovoltaic Materials using AFM
Organic photovoltaic (OPV) materials are inherently inhomogeneous at the nanometer scale. Nanoscale inhomogeneity of OPV materials affects performance of photovoltaic devices. In this paper, we describe a protocol for quantitative measurements of electrical and mechanical properties of OPV materials with sub-100 nm resolution.
Modified Yeast-Two-Hybrid System to Identify Proteins Interacting with the Growth Factor Progranulin
We have modified the conventional yeast two-hybrid screening, an effective genetic tool in identifying protein interaction. This modification markedly shortens the process, reduces the workload, and most importantly, reduces the number of false positives. In addition, this approach is reproducible and reliable.
High-Resolution Endocardial and Epicardial Optical Mapping in a Sheep Model of Stretch-Induced Atrial Fibrillation
This report provides a detailed description of the methodology and results of simultaneous endocardial and epicardial optical mapping of electrical excitation in the intact left atrium of a Langendorff-perfused sheep heart during stretch-induced atrial fibrillation.
1Department of Biochemistry & Molecular Biology, Wayne State University School of Medicine, 2Cardiovascular Research Institute, Wayne State University School of Medicine, 3Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine
Cystic fibrosis transmembrane conductance regulator (CFTR), an epithelial chloride channel, has been reported to interact with various proteins and regulate important cellular processes; among them the CFTR PDZ motif-mediated interactions have been well documented. This protocol describes methods we developed to assemble a PDZ-dependent CFTR macromolecular signaling complex in vitro.
1Department of Electrical and Computer Engineering, Boston University, 2Department of Biomedical Engineering, Boston University, 3Center for Advanced Genomics Technology, Boston University, 4Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, 5Department of Microbiology, Boston University School of Medicine, 6CNR (National Research Council), Istituto di Chimica del Riconoscimento Molecolare
Quantitative, high-throughput, real-time, and label-free biomolecular detection (DNA, protein, etc.) on SiO2 surfaces can be achieved using a simple interferometric technique which relies on LED illumination, minimal optical components, and a camera. The Interferometric Reflectance Imaging Sensor (IRIS) is inexpensive, simple to use, and amenable to microarray formats.
Colorectal Cancer Cell Surface Protein Profiling Using an Antibody Microarray and Fluorescence Multiplexing
1School of Molecular Bioscience, University of Sydney, 2Department of Surgery, Royal Prince Alfred Hospital, 3Department of Anatomical Pathology, Department of Anatomical Pathology, 4Department of Medicine, Concord Repatriation General Hospital
We described a procedure for the disaggregation of colorectal cancer (CRC) to produce viable single cells, which are then captured on customized antibody microarrays recognizing surface antigens (DotScan CRC microarray). Sub-populations of cells bound to the microarray can be profiled by fluorescence multiplexing using monoclonal antibodies tagged with fluorescent dyes.
Tandem affinity purification is a robust approach for the identification of protein binding partners. As proof of concept, this methodology was applied to the well-characterized translation initiation factor eIF4E to co-precipitate the host cell factors involved in translation initiation. This method is easily adapted to any cellular or viral protein.
A high-content screening method for the identification of novel signaling competent transmembrane receptors is described. This method is amenable to large-scale automation and allows predictions about in vivo protein binding and the sub-cellular localization of protein complexes in mammalian cells.
Avidity-based Extracellular Interaction Screening (AVEXIS) for the Scalable Detection of Low-affinity Extracellular Receptor-Ligand Interactions
AVEXIS is a high throughput protein interaction assay developed to systematically screen for novel extracellular receptor-ligand pairs involved in cellular recognition processes. It is specifically designed to detect transient protein interactions that are difficult to identify using other high throughput approaches.
A general protocol for the study of invasion of host cells by a bacterial pathogen, focusing on Staphylococcus aureus and human endothelial cells.
FRET-based reporters are increasingly used to monitor kinase and phosphatase activities in live cells. Here we describe a method on how to use FRET-based reporters to assess cell cycle-dependent changes in target phosphorylation.
This video shows how morpholino or mRNA can be injected into zebrafish embryos at the one-cell stage to decrease or increase the level of specific gene products during subsequent development.
In situ subcellular fractionation of mammalian cells on microscope coverslips allows the visualisation of protein localisation.
1Department of Pathology, Hershey Medical Center, Pennsylvania State University, 2Department of Chemistry, Pennsylvania State University, 3Departments of Pathology, and Biochemistry and Molecular Biology, Hershey Medical Center, Pennsylvania State University, 4Materials Research Institute, Pennsylvania State University
SELEX protocols comprise multiple rounds of selection, each of which require regeneration of bound ligands, which in turn require fixed primer sequences flanking the random library regions. These fixed primer sequences can interfere with the selection process (false positives and negatives). Here we present a primer-free protocol.
1Division of Cardiovascular Medicine, Department of Medicine, Stanford University Medical Center, 2Division of Cardiology, Department of Medicine, University of California, San Francisco, 3San Francisco VAMC
Early detection of apoptosis may identify at-risk cell populations in a variety of diseases. Here we demonstrate a method to link an early apoptosis-detection protein (Annexin V) to a MRI-detectable iron oxide nanoparticle (SPIO). This method may be extended to other proteins of interest to generate MRI-detectable molecular imaging probes.
Biochemical Reconstitution of Steroid Receptor•Hsp90 Protein Complexes and Reactivation of Ligand Binding
1College of Nursing, Interdisciplinary Life Sciences Research Laboratory, Seattle University, 2College of Science and Engineering, Interdisciplinary Life Sciences Research Laboratory, Seattle University, 3School of Medicine, University of Washington
An in vitro method for preparing functional glucocorticoid receptor (GR)•hsp90 protein complexes from purified proteins and cellular lysates is described. The method utilizes immunoadsorption of recombinant GR followed by salt-stripping and protein complex reconstitution. The importance of cofactors and buffer conditions are discussed, as are potential method applications.
We have developed a cell fusion assay that quantifies SNARE-mediated membrane fusion events by activated expression of β-galactosidase.
Clathrin-mediated endocytosis depends on adaptor proteins that coordinate cargo selection and clathrin coat assembly. Here we describe procedures to study adaptor-clathrin physical interaction and live cell imaging approaches using as a model the yeast endocytic adaptor protein Sla1p.
A Convenient and General Expression Platform for the Production of Secreted Proteins from Human Cells
In the post-human genomics era, the availability of recombinant proteins in native conformations is crucial to structural, functional and therapeutic research and development. Here, we describe a test- and large-scale protein expression system in human embryonic kidney 293T cells that can be used to produce a variety of recombinant proteins.
Analyzing the Function of Small GTPases by Microinjection of Plasmids into Polarized Epithelial Cells
This article details the procedures involved in overexpression and analysis of small GTPases in polarized epithelial cells using microinjection technique.
The CompoZr Custom Zinc-Finger Nuclease (ZFN) Service enables precise genome editing in any organism or cell line at any locus defined by the user. This article describes the process for the design, manufacture, validation and implementation of the CompoZr Custom ZFN Service.
This protocol utilizes a pull down assay to determine the levels of active RhoC GTPase within cells.
Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.
Calmodulin (CaM) pull-down assay is an effective way to investigate the interaction of CaM with various proteins. This method uses CaM-sepharose beads for efficient and specific analysis of CaM-binding proteins. This provides an important tool to explore CaM signaling in cellular function.
The IP-FCM method is presented, which allows a sensitive, robust, biochemical assessment of native protein-protein interactions, without requiring genetic engineering or large sample sizes.
Here we demonstrate a protocol to carry out live cell staining that can be used to detect odorant receptors on the surface of HEK293T cells conveniently. In addition, it may also be used to assay for surface expression of other chemosensory receptors or GPCRs.
Adhesion Frequency Assay for In Situ Kinetics Analysis of Cross-Junctional Molecular Interactions at the Cell-Cell Interface
An adhesion frequency assay for measuring receptor-ligand interaction kinetics when both molecules are anchored on the surfaces of the interacting cells is described. This mechanically-based assay is exemplified using a micropipette-pressurized human red blood cell as adhesion sensor and integrin αLβ2 and intercellular adhesion molecule-1 as interacting receptors and ligands.
Measuring the yaw torque of tethered Drosophila with the torque meter allows the neuroscientist exquisite control of the stimulus situation of the experimental animal. Together with the unique genetic tools available in the fruit fly, this paradigm is used for a wide variety of neurobiological research.
1Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, 2London Regional Cancer Program, Children's Health Research Institute, and Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario
Determining the cell cycle position of a population of cells, or understanding how signals affect proliferation, can be readily measured by flow cytometry using this protocol. We report a simple experimental approach to staining cells and quantifying their position in the cell cycle.
This technical article describes a standard western-blotting procedure using the commercially available NuPAGE electrophoresis Mini-Gel system from Invitrogen.
In order to study the changes of nociceptive intraepidermal nerve fibers (IENFs) in painful neuropathies (PN), we developed protocols that could directly examine three-dimensional morphological changes observed in nociceptive IENFs. Three-dimensional analysis of IENFs has the potential to evaluate the morphological changes of IENF in PN.
T lymphocyte migration occurs during homing to lymphoid organs, exit from the vasculature, and entering into peripheral tissues. Here, we describe a protocol that can be used to analyze T lymphocyte migration in vitro.
Biochemically-defined large unilamellar vesicles (LUVs) are a convenient model system to analyze BCL-2 family interactions with immediate implications in better understanding the mitochondrial pathway of apoptosis. A method to produce LUVs, along with standard BCL-2 family protein combinations and controls to examine LUV permeabilization, are presented.