title: The plaque protein myozap identified as a novel major component of adhering junctions in endothelia of the blood and the lymph vascular systems.
abstract: Recently the protein myozap, a 54-kD polypeptide which is not a member of any of the known cytoskeletal and junctional protein multigene families, has been identified as a constituent of the plaques of the composite junctions in the intercalated disks connecting the cardiomyocytes of mammalian hearts. Using a set of novel, highly sensitive and specific antibodies we now report that myozap is also a major constituent of the cytoplasmic plaques of the adherens junctions (AJs) connecting the endothelial cells of the mammalian blood and lymph vascular systems, including the desmoplakin-containing complexus adhaerentes of the virgultar cells of lymph node sinus. In light and electron microscopic immunolocalization experiments we show that myozap colocalizes with several proteins of desmosomal plaques as well as with AJ-specific transmembrane molecules, including VE-cadherin. In biochemical analyses, rigorous immunoprecipitation experiments have revealed N-cadherin, desmoplakin, desmoglein-2, plakophilin-2, plakoglobin and plectin as very stably bound complex partners. We conclude that myozap is a general component of cell-cell junctions not only in the myocardium but also in diverse endothelia of the blood and lymph vascular systems of adult mammals, suggesting that this protein not only serves a specific role in the heart but also a broader set of functions in the vessel systems. We also propose to use myozap as an endothelial cell type marker in diagnoses.
authors: Helmholtz Group Cell Biology, German Cancer Research Center, DKFZ, Heidelberg, Germany.
authors: Sebastian
authors: S
authors: Pieperhoff
authors: Steffen
authors: S
authors: Rickelt
authors: Hans
authors: H
authors: Heid
authors: William C
authors: WC
authors: Claycomb
authors: Ralf
authors: R
authors: Zimbelmann
authors: Caecilia
authors: C
authors: Kuhn
authors: Stefanie
authors: S
authors: Winter-Simanowski
authors: Christian
authors: C
authors: Kuhn
authors: Norbert
authors: N
authors: Frey
authors: Werner W
authors: WW
authors: Franke
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism*; D000818:Animals; D000918:Antibody Specificity / Q000276:immunology; D002417:Cattle; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D042783:Endothelial Cells / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008196:Lymph / Q000378:metabolism*; D042601:Lymphatic Vessels / Q000378:metabolism*; D008565:Membrane Proteins / Q000097:blood* / Q000378:metabolism*; D051379:Mice; D009206:Myocardium / Q000166:cytology; D032383:Myocytes, Cardiac / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D034421:Sus scrofa
chemical_list: D008565:Membrane Proteins