Localization of the human 64kD autoantigen D1 to myofibrils in a subset of extraocular muscle fibers.
OBJECTIVE
To evaluate the tissue-specific expression pattern of the 64kD human autoantigen D1, a tropomodulin-related protein that may be involved in thyroid-associated ophthalmopathy.


METHODS
Recombinant 64kD human autoantigen D1 was generated in a bacterial expression system and used to immunize rabbits. Specific antibodies were affinity-purified and used for Western blots on normal and hyperthyroid rat and rabbit tissue, and immunofluorescence localization on cryosections of rat tissue.


RESULTS
Anti-64kD human autoantigen D1 antibodies recognize specifically a approximately 70kD polypeptide in western blots of extraocular muscle, sternothyroid muscle, and smooth muscle. Immunofluorescence staining demonstrates that the 64kD human autoantigen D1 localizes to myofibrils in slow fibers from rat extraocular and sternothyroid muscle. The level of this protein is not altered in extraocular muscles from hyperthyroid rabbits.


CONCLUSIONS
The 64kD human autoantigen D1 is expressed in slow fibers of extraocular and sternothyroid muscles as a component of myofibrils, and is not upregulated in conditions of hyperthyroidism.
Conley
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CA
Department of Cell Biology, MB24, The Scripps Research Institute 10550 N. Torrey Pines Rd., CA 92037, La Jolla, USA. cconley@mail.arc.nasa.gov
Fowler
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D000199:Actins / Q000378:metabolism; D000818:Animals; D001324:Autoantigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D003598:Cytoskeletal Proteins; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D006111:Graves Disease / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009210:Myofibrils / Q000378:metabolism* / Q000473:pathology; D009218:Myosins / Q000378:metabolism; D009801:Oculomotor Muscles / Q000378:metabolism* / Q000473:pathology; D011506:Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D014335:Tropomyosin / Q000378:metabolism
D000199:Actins; D001324:Autoantigens; D003598:Cytoskeletal Proteins; D007074:Immunoglobulin G; C103926:LMOD1 protein, human; D011506:Proteins; D011994:Recombinant Proteins; D014335:Tropomyosin; D009218:Myosins