Western blotting

Western blotting
Name	Western blotting
Invented	1979
Inventor	George H. Towbin; Edwin M. Southern; David G. Lane
Purpose	Protein detection and analysis
Synonyms	immunoblotting

Western blotting is an analytical technique for detecting specific proteins separated by electrophoresis and transferred to a membrane. Developed in the late 1970s, it is widely used in molecular biology laboratories associated with institutions like Max Planck Society, Cold Spring Harbor Laboratory, Stanford University, and Massachusetts Institute of Technology. The method underpins research cited in publications from journals such as Nature, Science, and Cell and is employed across projects funded by agencies including the National Institutes of Health, Wellcome Trust, and European Research Council.

Introduction

Western blotting combines gel electrophoresis, membrane transfer, and immunodetection to identify proteins of interest. Key historical contributors include George H. Towbin, Edwin M. Southern, and David G. Lane, whose work built upon techniques from laboratories at University of Geneva and Imperial College London. The technique complements assays such as those used in laboratories affiliated with Howard Hughes Medical Institute and methods developed in the context of projects at Salk Institute and Karolinska Institutet.

Principles and Workflow

The workflow begins with protein extraction from cells or tissues sourced from models like Mus musculus, Saccharomyces cerevisiae, Escherichia coli, or clinical samples from centers such as Mayo Clinic and Johns Hopkins Hospital. Proteins are separated by size using sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE), a method refined in research environments including University of Cambridge and University of California, Berkeley. After electrophoresis, proteins are transferred to membranes made of nitrocellulose or polyvinylidene difluoride (PVDF) in apparatuses produced by companies like Bio-Rad Laboratories and Thermo Fisher Scientific. Detection employs primary antibodies raised by suppliers or labs associated with Rockefeller University and visualized via secondary antibodies conjugated to enzymes such as horseradish peroxidase (HRP) or fluorescent tags used in platforms from GE Healthcare and LI-COR Biosciences. Signal development can use chemiluminescence, colorimetric substrates, or fluorescence, with imaging systems developed at places like Nikon Corporation and Fujifilm.

Reagents and Materials

Critical reagents include lysis buffers formulated following protocols from groups at University of Oxford and Yale University, protease and phosphatase inhibitors provided by vendors like Sigma-Aldrich, and prestained protein ladders standardized by organizations such as National Institute of Standards and Technology. Antibodies may be monoclonal or polyclonal produced by companies like Abcam or academic cores at University of Pennsylvania. Blocking agents such as bovine serum albumin (BSA) or nonfat dry milk are used as in studies affiliated with University of Chicago and Columbia University. Consumables include transfer buffers, electrophoresis rigs, and membranes sourced from manufacturers with supply chains involving Thermo Fisher Scientific, Merck Group, and distributors used by laboratories at University of Tokyo.

Variations and Advanced Techniques

Several adaptations extend capability: dot blot and slot blot variants used in clinical labs at Cleveland Clinic; two-dimensional electrophoresis linking to proteomics centers like European Molecular Biology Laboratory; far-Western blotting inspired by interaction studies in groups at University of California, San Diego; and quantitative fluorescent Westerns developed with instrumentation from LI-COR Biosciences. Reverse-phase protein arrays used in consortia such as The Cancer Genome Atlas and near-infrared detection strategies applied in collaborations with Massachusetts General Hospital expand throughput. Techniques integrating mass spectrometry—work performed at facilities like EMBL-EBI and Broad Institute—combine transfer-based detection with peptide identification.

Quantification and Data Analysis

Quantification requires careful controls established in protocols from institutions including Imperial College London and Duke University Medical Center. Densitometry of bands uses software from vendors such as Bio-Rad Laboratories or open-source tools developed at European Bioinformatics Institute, with normalization strategies referencing housekeeping proteins studied in cohorts at Karolinska Institutet. Statistical analysis of replicate data is guided by standards from American Society for Biochemistry and Molecular Biology and best-practice frameworks promoted by journals like The Lancet, with reproducibility concerns highlighted in reports by National Academy of Sciences and funding bodies such as National Science Foundation.

Applications and Limitations

Applications span signal transduction research in labs at University of California, San Francisco and biomarker validation in translational centers like Dana-Farber Cancer Institute. Clinical diagnostics in pathology departments at Mayo Clinic and research into infectious diseases at Centers for Disease Control and Prevention employ variants adapted for sensitivity and specificity. Limitations include antibody specificity issues raised in reviews from groups at Yale School of Medicine and semiquantitative nature noted by panels convened by Wellcome Trust. Alternative or complementary methods include enzyme-linked immunosorbent assay (ELISA) used in programs at WHO and targeted proteomics implemented at Howard Hughes Medical Institute-funded cores.

Category:Laboratory techniques