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Biomedical subjects

G Gerisch

Publications and source records attributed to G Gerisch.

At least 163 records · Page 9Linked to original sources
PubMed1973

Quantitation of membrane sites in aggregating Dictyostelium cells by use of tritiated univalent antibody.

Cell-to-cell adhesion during aggregation of Dictyostelium discoideum cells is completely blocked by univalent antibody (Fab) directed against two classes of target sites: surface structures characteristic for aggregation-competent cells ("contact sites A") and others present also on growth-phase cells ("contact sites B"). 3 x 10(5) Fab molecules bound per cell are sufficient to block contact sites A completely, although the Fab fragments cover not more than 2% of the total cell surface. Up to 8-fold this value can be bound per cell when Fab fragments of another specificity are used, without affecting activity of contact sites A. Blockage of cell-to-cell adhesion therefore depends on the binding of Fab fragments to specific target sites, rather than on the total number of Fab molecules bound per cell. This conclusion is also valid for cell adhesion attributed to contact sites B. Contact sites therefore represent a special class of cell-surface sites which, in cell homogenates as well as in vivo, can be traced by Fab, and which are not identical with the bulk of cell-surface antigens present on aggregating cells.

Agglutination↗
PubMed1973

Dynamics of antigenic membrane sites relating to cell aggregation in Dictyostelium discoideum.

Membrane interaction in aggregating cells of Dictyostelium discoideum can be blocked by univalent antibodies directed against specific membrane sites. Using a quantitative technique for measuring cell association, two classes of target sites for blocking antibodies were distinguished and their developmental dynamics studied. One class of these sites is specific for aggregation-competent cells, their quantity rising from virtually 0-level during growth, with a steep increase shortly before cell aggregation. The serological activity of these structures is species specific; they are not detectable in a nonaggregating mutant, but present in a revertant undergoing normal morphogenesis. Patterns of cell assembly in the presence of antibodies show that selective blockage of these membrane sites abolishes the preference for end-to-end association which is typical for aggregating cells. A second class of target sites is present in comparable quantities in particle fractions from both growth-phase and aggregation-competent cells. Blockage of these sites leads to aggregation patterns in which the side-by-side contacts of aggregating cells are abolished. The target sites of aggregation-inhibiting antibodies are suggested to be identical or associated with the molecular units of the cell membrane that mediate cell-to-cell contacts during aggregation. The results indicate that in one cell, two independent classes of contact sites can be simultaneously active.

Binding Sites, Antibody↗