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| actin | |
|---|---|
| Name | Actin |
| Organism | Eukaryota, Bacteria, Archaea |
| Length | ~375 amino acids (eukaryotic) |
actin Actin is a highly conserved, abundant protein ubiquitous across eukaryotic cells and present in prokaryotic homologs, central to cytoskeletal architecture, motility, and force generation. Discovered in studies of muscle contraction and cell motility, actin interacts with numerous motors, scaffolds, and signaling systems to coordinate processes from cytokinesis to morphogenesis. Research on actin spans work by laboratories associated with Harvard University, Stanford University, Max Planck Society, Cold Spring Harbor Laboratory, and funding from institutions such as the National Institutes of Health and European Research Council.
Eukaryotic actin folds into a globular monomer (G-actin) that polymerizes into a polarized filament (F-actin), with structural insights provided by cryo-electron microscopy and X-ray studies at facilities like European Synchrotron Radiation Facility and Brookhaven National Laboratory; mutations in conserved residues alter interactions with partners studied at centers including Johns Hopkins University and Massachusetts Institute of Technology. Multiple isoforms arise from gene families such as ACTA1 in skeletal muscle, ACTB in nonmuscle cells, and ACTG1 in smooth muscle and neuronal tissues, each encoded on chromosomes characterized in projects like the Human Genome Project and annotated by databases curated by National Center for Biotechnology Information. Comparative genomics across taxa including Drosophila melanogaster, Saccharomyces cerevisiae, Caenorhabditis elegans, Arabidopsis thaliana, and vertebrates reveal conservation and diversification linked to development programs governed by regulators studied at institutions like European Molecular Biology Laboratory.
Polymerization involves nucleation, elongation, and steady-state treadmilling influenced by nucleotide state (ATP/ADP) characterized in biochemical assays pioneered in labs at University of Cambridge and University of Oxford; kinetic models were developed alongside computational work from groups at Columbia University and University of California, Berkeley. Dynamic turnover is regulated by severing and capping events observed in vitro and in vivo using techniques advanced at Max Planck Institute for Biophysical Chemistry and Howard Hughes Medical Institute, with actin filament behavior integrated into systems-level models used by researchers at Princeton University and ETH Zurich. In vitro reconstitution of actin networks with proteins from laboratories such as Institute Pasteur and University of Tokyo has linked filament mechanics to cellular-scale behaviors analyzed in collaborations with European Molecular Biology Laboratory and engineering groups at Massachusetts Institute of Technology.
Actin networks generate contractile and protrusive forces fundamental to processes studied in contexts such as lamellipodia formation in cell migration work from Salk Institute for Biological Studies, endocytosis characterized by groups at Yale University, and cytokinesis investigated at Rockefeller University. In neurons, actin contributes to growth cone dynamics and synaptic plasticity researched at Columbia University Medical Center and University College London; in muscle, actin–myosin interactions underpin contraction mechanisms elucidated by teams at Kobe University and University of Pennsylvania. Cellular polarity, adhesion, and mechanotransduction involving focal adhesions and junctions have been examined in studies affiliated with University of California, San Francisco and Karolinska Institutet.
A wide array of binding proteins regulate nucleation, branching, capping, severing, and crosslinking: the Arp2/3 complex and nucleation-promoting factors identified in work from European Molecular Biology Laboratory and University of California, San Diego; formins characterized in studies at University of Chicago; cofilin family members studied at Max Planck Society; profilin analyzed by groups at University of Cambridge; tropomyosin and troponin complexes elucidated in muscle research at University of Tokyo and Johns Hopkins University. Signaling pathways modulating actin dynamics involve small GTPases such as Rho, Rac, and Cdc42, with pathway components mapped in research linked to National Institute of Child Health and Human Development and systems biology consortia at European Research Council.
During embryogenesis and morphogenesis, actin-driven cell shape changes and tissue movements have been documented in model systems like Xenopus laevis, Danio rerio, and Drosophila melanogaster by teams at Max Planck Institute for Developmental Biology and California Institute of Technology. Mutations in actin genes or dysregulation of binding partners cause myopathies, cardiomyopathies, and congenital syndromes reported in clinical studies at Mayo Clinic, Cleveland Clinic, and pediatric centers affiliated with Great Ormond Street Hospital. Actin remodeling contributes to cancer cell invasion and metastasis analyzed by oncology groups at Memorial Sloan Kettering Cancer Center and Dana-Farber Cancer Institute, and to neurodegenerative conditions investigated at National Institute of Neurological Disorders and Stroke and Mount Sinai Health System.
Visualization and manipulation tools include fluorescent phalloidin staining and GFP-tagging developed in molecular biology programs at University of California, San Diego and Whitehead Institute, live-cell imaging with total internal reflection fluorescence used by microscopy centers at European Molecular Biology Laboratory and Wellcome Trust Centre for Cell Biology, and super-resolution techniques advanced at Janelia Research Campus and University of Oxford. Biochemical assays for polymerization, co-sedimentation, and ATPase activity are standard in protocols from laboratories at Cold Spring Harbor Laboratory and Rockefeller University, while cryo-EM and cryo-ET structural studies at facilities like European Synchrotron Radiation Facility and EMBL provide atomic-resolution models. Genetic perturbation using CRISPR technologies from innovators at Broad Institute and high-throughput screens at Wellcome Sanger Institute enable functional dissection across organisms.
Category:Cytoskeletal proteins