Ultrastructural localization of lectin-binding sites in different basement membranes

1993 ◽  
Vol 25 (6) ◽  
pp. 464-468 ◽  
Author(s):  
Mehrdad Salamat ◽  
Werner G�tz ◽  
J�rgen Werner ◽  
Rainer Merken
1975 ◽  
Vol 66 (2) ◽  
pp. 263-274 ◽  
Author(s):  
G L Nicolson ◽  
R Yanagimachi ◽  
H Yanagimachi

Receptors for Ricinus communis agglutinin I (RCAI), concanavalin A (Con A), and wheat germ agglutinin (WGA) were localized on the zonae pellucidae and plasma membranes of hamster, mouse, and rat eggs with ferritin-lectin conjugates. Intact eggs labeled with the ferritin conjugates showed dense concentrations of RCAI and WGA receptors in the outermost regions of their zonae pellucidae and sparse distributions of Con A receptors throughout the zonae. Ferritin-lectin labeling was specific, since inhibitory saccharides effectively blocked labeling. The asymmetric density of RCAI receptors across the zona was confirmed by ferritin-RCAI and fluorescein-RCAI labeling of mechanically isolated zonae pellucidae, indicating that the RCAI-binding sites are more densely distributed in the exterior zona regions. Plasma membranes of rodent eggs contained RCAI, WGA, and Con A receptors. These receptors were found to be more or less randomly distributed on surfaces of aldehyde-fixed eggs or on eggs labeled near 0 degrees C. However, eggs incubated at 25 degrees C showed aggregated WGA- and Con A-binding site distributions on their plasma membranes. This indicates that lectin-induced receptor redistribution occurs at this temperature. The possibility that plasma membrane receptor mobility is a requirement for sperm-egg fusion is discussed.


1978 ◽  
Vol 29 (1) ◽  
pp. 287-296
Author(s):  
I. Virtanen ◽  
A. Miettinen ◽  
J. Wartiovaara

In the present study ultrastructural localization of binding sites for 5 lectins was studied in rat liver cell surface membrane fractions. For this purpose ferritin-coupled Concanavalin A, wheat germ agglutinin, soybean agglutinin, Ricinus communis agglutinin 120 and Lotus tetragonolobus agglutinin I were used as probes for mannose, N-acetyl glucosamine, N-acetyl galactosamine, galactose and fucose moieties in glycoproteins and glycolipids. Although recent reports suggest presence of glycogroups on the cytoplasmic surface of cellular membranes ultrastructural identification of membrane surfaces in the present study indicated an asymmetric localization of lectin-binding sites exclusively on the extracellular side of the membranes.


1998 ◽  
Vol 197 (4) ◽  
pp. 305-315 ◽  
Author(s):  
B. Nico ◽  
Fabio Quondamatteo ◽  
Domenico Ribatti ◽  
Mirella Bertossi ◽  
Giangiuseppe Russo ◽  
...  

1978 ◽  
Vol 24 (7) ◽  
pp. 785-793 ◽  
Author(s):  
H. E. Calvert ◽  
M. Lalonde ◽  
T. V. Bhuvaneswari ◽  
W. D. Bauer

The binding of purified, ferritin-labeled soybean seed lectin to the cell surfaces of Rhizobium japonicum 311b 138 has been examined by whole mount, thin section, and freeze-etch electron microscopy. The ferritin-labeled lectin binds in a biochemically specific manner to the capsular material of this bacterium. The lectin does not bind to the outer membranes of the cells or to flagella. Labeled lectin binds to sites throughout the capsular structure, although the density of labeling is somewhat greater on the outer surface of the capsule. Some cells appear to be partially encapsulated. Preservation of the capsular material proved difficult, and methods for retaining most of the capsular material were developed.


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