Discoidin I-membrane interactions III. Interaction of discoidin I with living Dictyostelium discoideum cells

Bartles, James R.; Santoro, Barbara; Frazier, William A.

doi:10.1016/0005-2736(82)90539-9

Cited by 7 publications

(6 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, the lectins did not detectably adsorb adhesion-blocking Fab. Electrostatic interaction of discoidin I with biological membranes has been reported by Bartles and co-workers (7,9). However, inhibitors of this interaction, such as heparin, have no effect on the EDTA-resistant cohesion of D. discoideum cells (8,9).…”

Section: Discussionmentioning

confidence: 92%

“…Electrostatic interaction of discoidin I with biological membranes has been reported by Bartles and co-workers (7,9). However, inhibitors of this interaction, such as heparin, have no effect on the EDTA-resistant cohesion of D. discoideum cells (8,9). These investigators have also failed to detect immunoreactive discoidin I on the surface of aggregationcompetent NC-4 or A3 cells (6,9).…”

Section: Discussionmentioning

confidence: 93%

“…Evidence against the involvement of the discoidins in cellcell cohesion has been reported and has been extensively considered by Bartles and colleagues (5,6,9). These data deal with the effect of competitive inhibitors and antagonists of the discoidins on cell cohesion.…”

Section: Discussionmentioning

confidence: 99%

“…However, inhibitors of this interaction, such as heparin, have no effect on the EDTA-resistant cohesion of D. discoideum cells (8,9). These investigators have also failed to detect immunoreactive discoidin I on the surface of aggregationcompetent NC-4 or A3 cells (6,9). In addition, D. discoideum cells can apparently display maximal cohesiveness while exhibiting miniscule amounts of discoidin I on their surfaces or in the surrounding medium (9).…”

Section: Discussionmentioning

confidence: 99%

“…Affinity Purification: Discoidins I and II were co-purified from cellfree extracts of strains A3 and NC-4 on acid-treated Sepharose 6B (9). Protein concentrations were determined by the method of Lowry et al (27) using BSA as a standard.…”

Section: Methodsmentioning

confidence: 99%

See 4 more Smart Citations

Failure to detect immunocytochemically reactive endogenous lectin on the cell surface of Dictyostelium discoideum.

Erdos¹,

Whitaker²

1983

The Journal of Cell Biology

View full text Add to dashboard Cite

The endogenous lectins of Dictyostelium discoideum, called discoidins I and II, have been implicated in cell cohesion during the associative phase of this organism. In an effort to repeat and extend the studies of these putative cell-surface proteins, we attempted a variety of immunocytochemical techniques. Antibodies to a mixture of the purified discoidins were raised in rabbit. Both living and fixed cells were examined by indirect immunoferritin labeling using whole antiserum and by direct immunolabeling using purified specific IgG adsorbed to colloidal gold. Cells, at the appropriate stage, of strains A3, NC-4, and WS-582 were tested. In no instance were cell surface antigens detected despite meticulous efforts to duplicate the published techniques and to extend and refine them. Specific localization was found only in the cytosol and on the cytoplasmic face of certain endomembrane vesicles, and much less so on outer nuclear and mitochondrial membranes, in inadvertently disrupted cells. In no case was specific label found on either side of the plasma membrane or on food vacuoles. Exogenously supplied discoidins, bound to cells, were successfully localized by our technique. We conclude that the discoidins are not present on the cell surface, or are there in undetectable quantities, during the associative phase. We suggest that previous demonstrations of these proteins at the cell surface were artifacts resulting from the way in which the cells were handled, which caused the binding of externalized discoidins, possibly those released from lysed cells. We believe that the current notion that the discoidins play a direct role in cell cohesion by virtue of their carbohydrate-binding capacity should be reexamined. We suggest that the true role of the discoidins is solely intracellular.

show abstract

Section: Discussionmentioning

confidence: 92%