Ultrastructure of the zonula adherens revealed by rapid-freeze deep-etching. 2000

K Miyaguchi
Laboratory of Neurobiology, NINDS, NIH, Bethesda, Maryland 20892, USA. kmiyagu@neurol.med.osaka-u.ac.jp

The zonula adherens (ZA) in adult chicken retinal pigment epithelium was examined with cryo-electron microscopic methods. Deep-etching of the cross-fractured ZA showed globules in the intercellular space. These globules apparently correspond to the electron-dense structure seen in thin sections. Deep-etching of obliquely fractured ZA further revealed rod-like structures extending from the extracellular surface into the intercellular space. These rods (mean approximately 9 nm thick, approximately 20 nm long) were straight and sometimes divided into two or three segments. The rods typically canted at approximately 60 degrees with respect to the plasma membrane, and they were often connected to the intercellular globules at their distal ends. When the rods are compared with the isolated cadherins reported previously, it is suggested that a combination of a rod and a globule may represent an extracellular part of cadherin. Membrane particles were observed on the P-face of the ZA plasma membrane, and their distribution density was approximately seven times that of the rods. The freeze-etching also revealed a characteristic particle complex on the ZA cytoplasmic surface, which may represent the cytosolic proteins linking cadherins to actin bundles.

UI MeSH Term Description Entries
D010857 Pigment Epithelium of Eye The layer of pigment-containing epithelial cells in the RETINA; the CILIARY BODY; and the IRIS in the eye. Eye Pigment Epithelium
D002645 Chickens Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA. Gallus gallus,Gallus domesticus,Gallus gallus domesticus,Chicken
D003593 Cytoplasm The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990) Protoplasm,Cytoplasms,Protoplasms
D005613 Freeze Etching A replica technique in which cells are frozen to a very low temperature and cracked with a knife blade to expose the interior surfaces of the cells or cell membranes. The cracked cell surfaces are then freeze-dried to expose their constituents. The surfaces are now ready for shadowing to be viewed using an electron microscope. This method differs from freeze-fracturing in that no cryoprotectant is used and, thus, allows for the sublimation of water during the freeze-drying process to etch the surfaces. Etching, Freeze
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D015820 Cadherins Calcium-dependent cell adhesion proteins. They are important in the formation of ADHERENS JUNCTIONS between cells. Cadherins are classified by their distinct immunological and tissue specificities, either by letters (E- for epithelial, N- for neural, and P- for placental cadherins) or by numbers (cadherin-12 or N-cadherin 2 for brain-cadherin). Cadherins promote cell adhesion via a homophilic mechanism as in the construction of tissues and of the whole animal body. Cadherin,E-Cadherins,Epithelial-Cadherin,Liver Cell Adhesion Molecules,N-Cadherins,Neural Cadherin,P-Cadherins,Uvomorulin,Cadherin-1,Cadherin-2,Cadherin-3,E-Cadherin,Epithelial-Cadherins,Liver Cell Adhesion Molecule,N-Cadherin,Neural Cadherins,P-Cadherin,Placental Cadherins,Cadherin 1,Cadherin 2,Cadherin 3,Cadherin, Neural,Cadherins, Neural,Cadherins, Placental,E Cadherin,E Cadherins,Epithelial Cadherin,Epithelial Cadherins,N Cadherin,N Cadherins,P Cadherin,P Cadherins
D017948 Retinal Rod Photoreceptor Cells Photosensitive afferent neurons located in the peripheral retina, with their density increases radially away from the FOVEA CENTRALIS. Being much more sensitive to light than the RETINAL CONE CELLS, the rod cells are responsible for twilight vision (at scotopic intensities) as well as peripheral vision, but provide no color discrimination. Photoreceptors, Rod,Retinal Rod Cells,Rod Photoreceptors,Rods (Retina),Retinal Rod,Retinal Rod Cell,Retinal Rod Photoreceptor,Retinal Rod Photoreceptors,Rod Photoreceptor Cells,Cell, Retinal Rod,Cell, Rod Photoreceptor,Cells, Retinal Rod,Cells, Rod Photoreceptor,Photoreceptor Cell, Rod,Photoreceptor Cells, Rod,Photoreceptor, Retinal Rod,Photoreceptor, Rod,Photoreceptors, Retinal Rod,Retinal Rods,Rod (Retina),Rod Cell, Retinal,Rod Cells, Retinal,Rod Photoreceptor,Rod Photoreceptor Cell,Rod Photoreceptor, Retinal,Rod Photoreceptors, Retinal,Rod, Retinal,Rods, Retinal
D020285 Cryoelectron Microscopy Electron microscopy involving rapid freezing of the samples. The imaging of frozen-hydrated molecules and organelles permits the best possible resolution closest to the living state, free of chemical fixatives or stains. Electron Cryomicroscopy,Cryo-electron Microscopy,Cryo electron Microscopy,Cryo-electron Microscopies,Cryoelectron Microscopies,Cryomicroscopies, Electron,Cryomicroscopy, Electron,Electron Cryomicroscopies,Microscopies, Cryo-electron,Microscopies, Cryoelectron,Microscopy, Cryo-electron,Microscopy, Cryoelectron
D022005 Adherens Junctions Anchoring points where the CYTOSKELETON of neighboring cells are connected to each other. They are composed of specialized areas of the plasma membrane where bundles of the ACTIN CYTOSKELETON attach to the membrane through the transmembrane linkers, CADHERINS, which in turn attach through their extracellular domains to cadherins in the neighboring cell membranes. In sheets of cells, they form into adhesion belts (zonula adherens) that go all the way around a cell. Zonula Adherens,Adherens Junction,Adherens, Zonula,Junction, Adherens,Junctions, Adherens

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