title: Protein myozap--a late addition to the molecular ensembles of various kinds of adherens junctions.
abstract: The protein myozap, a polypeptide of 54 kDa, has recently been identified as a component of the cytoplasmic plaques of the composite junctions (areae compositae) in the myocardiac intercalated disks and of the adherens junctions (AJs) in vascular endothelia. Now we report that using very sensitive new antibodies and drastic localization methods, we have also identified this protein as a component of the AJ plaques in simple and complex epithelia, in the adluminal cell layer of the transitional epithelium of the urinary tract and in certain cell layers of diverse stratified epithelia, including gingiva, tongue, pharynx and esophagus, cervix, vagina and epidermis. Myozap has not been identified in desmosomal and tight junction plaques. We have also detected protein myozap in AJ structures of carcinomas. The discovery of a novel major protein in AJ plaques now calls for re-examinations of molecular interactions in AJ formation and maintenance and also offers a new marker for diagnostic immunocytochemistry. We also discuss the need for progressive unravelling, extractive treatments and buffer rinses of sections and cultured cells to reveal obscured or masked antigens, before definitive negative conclusions in immunohistochemistry can be made.
authors.affiliation: Helmholtz Group for Cell Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Rickelt
authors.forename: Caecilia
authors.initials: C
authors.lastname: Kuhn
authors.forename: Stefanie
authors.initials: S
authors.lastname: Winter-Simanowski
authors.forename: Ralf
authors.initials: R
authors.lastname: Zimbelmann
authors.forename: Norbert
authors.initials: N
authors.lastname: Frey
authors.forename: Werner Wilhelm
authors.initials: WW
authors.lastname: Franke
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002448:Cell Adhesion / Q000502:physiology; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D019108:Tight Junctions / Q000378:metabolism; D062826:Zonula Occludens-1 Protein
chemical_list: D008565:Membrane Proteins; D009124:Muscle Proteins; D010750:Phosphoproteins; C569043:Tjp1 protein, mouse; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein