Intercellular adhesion in the cellular slime mold Polysphondylium pallidum inhibited by interaction of asialofetuin or specific univalent antibody with endogenous cell surface lectin☆

[摘要] Previousworkhasshownthat,asamoebaeofthecellularslimemoldPolysphondyliumpallidumbecomeaggregationcompetent,theyaccumulateontheircellsurfaceacarbohydrate-bindingprotein(lectin)namedpallidin.Theseamoebaealsopossesscellsurfacereceptors,presumedtocontaincomplexoligosaccharideswithahighaffinityfortheendogenouslectin.Iflectin-receptorinteractionsmediatecell-cellcontact,thenappropriateconcentrationsofpallidininhibitorsshouldblockcellcohesion.Twopotentmacromolecularantagonistsofthelectinwereemployed:thedesialylatedformoftheglycoproteinfetuinandtheunivalentantibody(Fab)preparedagainstpallidin.Westudiedtheeffectsoftheseinhibitorsonrotation-mediatedaggregationofP.pallidumamoebaeunderavarietyofassayconditions.Amoebaeexposedtohypertonicconditionsortoantimetabolites(“Permissiveconditions”)wereselectivelyblockedfromassociatingbymicrogramquantitiesofthelectininhibitors,whereascellsinisotonicbuffer(“nonpermissivecondition”)wereonlyslightlyaffected.Acomparisonofthemorphologyofagglutinatesformedunderthevariousconditionsallowsseveralexplanationsforthedifferentsusceptibilitiestoinhibitionbyantipallidinreagents.Althoughnotconclusive,theworksupportsamodelofcelladhesioninthissimpleeukaryoticsystembasedatleastinpartonspecificinteractionsbetweencarbohydrate-bindingproteinsandreceptorsonadjoiningcells.

[学科分类] 生物科学（综合）