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Adhesion-blocking antibodies prepared against gp150 react with gp80 of Dictyostelium
Abstract:
A membrane glycoprotein of 150 000 D, gp150, has been implicated in the mechanism of cell-cell adhesion which arises during development of Dictyostelium discoideum. This conclusion was founded on the observation that monovalent Fab' fragments prepared from an antiserum raised against partially purified gp150 are able to block cell-cell adhesion. We show that this serum contains antibodies to a distinct membrane glycoprotein, gp80, previously implicated in cell-cell adhesion. Reaction of Fab' to this surface molecule can account for the adhesion-blocking activity in the antiserum to gp 150. Moreover, binding of gp80 neutralized Fab' to gp150 does not block adhesion. If gp150 carries other determinants which bind adhesion-blocking Fab', these determinants must also be present on gp80. Thus, it is not clear that gp150 is directly involved in cell-cell adhesion of Dictyostelium.
Insights
The study questions the direct role of glycoprotein 150 (gp150) in Dictyostelium discoideum cell-cell adhesion. Antibodies previously thought to target gp150 actually bind to gp80, a known adhesion molecule.
Area of Science:
- Cell Biology
- Developmental Biology
- Biochemistry
Background:
- Cell-cell adhesion is crucial for multicellular development in Dictyostelium discoideum.
- Membrane glycoprotein gp150 was previously implicated in mediating this adhesion process.
- Monovalent antibody fragments (Fab') against gp150 were shown to inhibit cell adhesion.
Purpose of the Study:
- To re-evaluate the role of gp150 in Dictyostelium discoideum cell-cell adhesion.
- To determine if antibodies against gp150 are specific or cross-react with other adhesion molecules.
- To clarify the molecular mechanisms underlying cell adhesion during development.
Main Methods:
- Production and characterization of a polyclonal antiserum against partially purified gp150.
- Preparation of monovalent Fab' fragments from the antiserum.
- Assessing the effect of Fab' fragments on Dictyostelium cell-cell adhesion.
- Immunological analysis to identify the specific targets of the antibodies in the antiserum.
Main Results:
- The antiserum against gp150 contains antibodies that also recognize membrane glycoprotein gp80.
- gp80 is a known mediator of cell-cell adhesion in Dictyostelium.
- Fab' fragments targeting gp80, but not gp150-specific fragments, effectively blocked cell adhesion.
- Adhesion-blocking activity of the anti-gp150 antiserum is attributable to antibodies against gp80.
Conclusions:
- The direct involvement of gp150 in Dictyostelium cell-cell adhesion is questionable.
- The adhesion-blocking activity previously attributed to gp150 is likely due to cross-reactivity with gp80.
- Further investigation is needed to elucidate the precise function of gp150, if any, in cell adhesion.