Calmodulin-like proteins and communicating junctions

1987 ◽  
Vol 408 (4) ◽  
pp. 379-385 ◽  
Author(s):  
Camillo Peracchia
Keyword(s):  
Communicating Junctions

Calmodulin-mediated gating of lens gap junction channels in vesicles

1984 ◽  
Vol 42 ◽  
pp. 134-137
Author(s):  
Camillo Peracchia ◽  
Stephen J. Girsch
Keyword(s):  
Gap Junctions ◽  
Freeze Fracture ◽  
Orthogonal Arrays ◽  
Eye Lens ◽  
Lens Fiber ◽  
Cell Coupling ◽  
Particle Spacing ◽  
Fiber Cells ◽  
Gap Junction Channels ◽  
Communicating Junctions

The fiber cells of eye lens communicate directly with each other by exchanging ions, dyes and metabolites. In most tissues this type of communication (cell coupling) is mediated by gap junctions. In the lens, the fiber cells are extensively interconnected by junctions. However, lens junctions, although morphologically similar to gap junctions, differ from them in a number of structural, biochemical and immunological features. Like gap junctions, lens junctions are regions of close cell-to-cell apposition. Unlike gap junctions, however, the extracellular gap is apparently absent in lens junctions, such that their thickness is approximately 2 nm smaller than that of typical gap junctions (Fig. 1,c). In freeze-fracture replicas, the particles of control lens junctions are more loosely packed than those of typical gap junctions (Fig. 1,a) and crystallize, when exposed to uncoupling agents such as Ca++, or H+, into pseudo-hexagonal, rhombic (Fig. 1,b) and orthogonal arrays with a particle-to-particle spacing of 6.5 nm. Because of these differences, questions have been raised about the interpretation of the lens junctions as communicating junctions, in spite of the fact that they are the only junctions interlinking lens fiber cells.

The mechanism of T cell mediated cytotoxicity IV. Studies on communicating junctions between cells in contact

1977 ◽  
Vol 196 (1122) ◽  
pp. 73-84 ◽  
Keyword(s):  
T Cell ◽  
Mammalian Cells ◽  
Cytotoxic T Cells ◽  
Diploid Cell ◽  
Target Cells ◽  
Cytotoxic Lymphocytes ◽  
Communicating Junctions ◽  
Unique System ◽  
Pass Through ◽  
Autoradiographic Technique

A modified autoradiographic technique has been developed which makes it possible to demonstrate the intercellular transfer of diffusible molecules through communicating junctions. This technique has been used to decide whether or not there is a cytoplasmic union between cytotoxic lymphocytes and the target cells they destroy. The transfer of 51 Cr, [ 3 H]uridine and [ 3 H]choline has been demonstrated between human diploid cell line cells (MRC 5) in contact. This has provided a system in which the techniques could be assessed. The demonstration that 51 Cr can pass through communicating junctions provides a unique system for the investigations of these structures. Despite the fact that all three labels could transfer between MRC 5 cells in contact, no transfer between cytotoxic T cells and P815 target cells could be demonstrated during a cytotoxic reaction. The reported transfer of fluorescein can probably be attributed to the transfer of fluorescein ester via the extracellular space. It is concluded, therefore, that communicating junctions of the type that can form between certain mammalian cells in contact do not contribute to the mechanism of T cell cytotoxicity.

A correlative freeze-etch and electrophysiological study of communicating junctions in crystalline lenses

1985 ◽  
Vol 4 (11) ◽  
pp. 1145-1153 ◽  
Author(s):  
J. R. Kuszak ◽  
Y. H. Shek ◽  
K. C. Carney ◽  
J. L. Rae
Keyword(s):  
Electrophysiological Study ◽  
Communicating Junctions

Lens junctions are communicating junctions

1985 ◽  
Vol 4 (11) ◽  
pp. 1155-1169 ◽  
Author(s):  
C. Peracchia ◽  
S. J. Girsch ◽  
G. Bernardini ◽  
L. L. Peracchia
Keyword(s):  
Communicating Junctions

Junctional structures in hydra

1977 ◽  
Vol 23 (1) ◽  
pp. 151-172
Author(s):  
B.K. Filshie ◽  
N.E. Flower
Keyword(s):  
Freeze Fracture ◽  
Septate Junctions ◽  
Detailed Understanding ◽  
Freeze Fracturing ◽  
Communicating Junctions ◽  
Lanthanum Tracer

The sealing and communicating junctions present in hydra have been examined using conventional staining, lanthanum tracer and freeze-fracturing techniques. The presence of distinct types of gap and septate junctions has been confirmed. Combined lanthanum tracer and freeze-fracture results have provided a more detailed understanding of these junctional structures. A model has been constructed which demonstrates the various aspects of the junction seen at different sectioning angles. The probable lengths of septa within septate junctions and the junctional ‘maze’ formed by them is discussed because of its bearing on the ‘sealing’ nature of the junction and also, to some extent, on its permeability to tracers such as lanthanum.

Identification and distribution of gap junctions in the mesoderm of the developing chick limb bud

Development ◽  
1978 ◽  
Vol 46 (1) ◽  
pp. 99-110
Author(s):  
Robert O. Kelley ◽  
John F. Fallon
Keyword(s):  
Electron Microscopy ◽  
Gap Junctions ◽  
Limb Development ◽  
Freeze Fracture ◽  
Mesenchymal Cells ◽  
Limb Bud ◽  
Metabolic Coupling ◽  
Transmission Electron ◽  
Communicating Junctions ◽  
Cell Processes

Sub-ridge, core, anterior and posterior borders of mesoderm were dissected from stages 22–24 chick wing buds to investigate whether structures for intercellular coupling develop between mesenchymal cells. Fine structure was examined using techniques of transmission electron microscopy, freeze-fracture and scanning electron microscopy. Gap (communicating) junctions which were observed between mesenchymal cells of all limb bud regions were distributed between apposed cell bodies, points of contact between cell processes and other cell bodies, and between contacting tips of slender cell projections. In addition, particularly in the subridge region, filopodia were observed to extend through the intercellular matrix to contact other cells several micrometers distant. The observations reported in this paper show that mesodermal cells throughout the limb have the structural capability for electrotonic and metabolic coupling during a critical period of morphogensisis in the avian limb. Whether intercellular signals which are thought to be transmitted through gap junctions are active in normal limb development remains to be investigated.

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