Two distinct adhesion mechanisms in embryonic neural retina cells: I. A kinetic analysis☆

[摘要] Thereaggregationkineticsofembryonicchickneuralretinacellspreparedusingseveraldifferentdissociationproceduresweremonitoredthroughdecreasesinthesmall-anglelightscatteringofaggregatingsamples.Twodistinctmodesofaggregationwererevealed,oneCa2+independent,theotherCa2+dependent,suggestingtheexistenceoftwoseparateadhesionmechanisms.ByvaryingtheconcentrationsofCa2+andtrypsininthedissociationmedium,weobtainedcellswhichexhibitedboth,either,orneithermodeofaggregation.TheCa2+-independentadhesivenessisactiveintheabsenceofproteolysis,isresistanttolowlevelsoftrypsin(0.001%),butisreadilyinactivatedathighertrypsinconcentrationsineitherthepresenceorabsenceofCa2+.Itisrelativelytemperatureindependent.Bycontrast,theCa2+-dependentadhesivenessisnotdetectedbeforeexposureofthecellstoproteolysis.ItisexpressedaftertrypticproteolysisinthepresenceofCa2+andisthenhighlytemperaturedependent.ItisresistanttofurtherdigestionbytrypsininthecontinuedpresenceofCa2+butislostwhenCa2+issubsequentlyremoved,apparentlythroughtheexpressionoftrypticcleavageincurredearlier.Wesuggestthatitsincreasedactivitymayresultatleastinpartfromtheclusteringofsurfacecomponentsintoadhesivepatches.Aprovisionalmodelispresentedcorrelatingthesedata.

[学科分类] 生物科学（综合）