Concanavalin A-induced cap formation in rat ascites hepatoma cells (AH 7974) and the interaction of cytoplasmic proteins with plasma membranes.
Concanavalin A (Con A) induced cap formation in rat ascites hepatoma cells (AH7974). In these Con A-treated cells, the association of cytoplasmic proteins with cell membranes was suggested by observing their Triton shells. The transition from G-actin to F-actin occurred in these cells. The association of membrane lipid with cytoplasmic proteins extracted from AH cells was studied by the isolation of protein-bound liposomes and phase transition release. The analysis of isolated liposomes revealed that many cytoplasmic proteins which specifically associated with liposomes were cytoskeletal elements including F-actins. The association of proteins with liposomes was affected by the lipid composition of the liposomal membrane and by the Ca2+ concentration of the incubation medium. The strong interaction of liposomal membrane with cytoplasmic proteins or isolated cytoskeletal proteins was demonstrated also by phase transition release using carboxy fluorescein-containing liposomes. These experiments showed that there was a strong affinity between lipid membrane and cytoskeletal elements including F-actins and that the amount of F-actin increased due to Con A treatment. The association of the submembranous microfilaments with the cell membrane may contribute to capping of the cells caused by Con A.
Moromizato
Y
Y
Department of Anatomy, Okayama University Medical School, Japan.
Watanabe
S
S
Sasaki
J
J
D000199:Actins / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure*; D003208:Concanavalin A / Q000494:pharmacology*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D003599:Cytoskeleton / Q000648:ultrastructure*; D007152:Immunologic Capping / Q000187:drug effects*; D008081:Liposomes; D008114:Liver Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology*; D008563:Membrane Lipids / Q000378:metabolism; D051381:Rats; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D000199:Actins; D003598:Cytoskeletal Proteins; D008081:Liposomes; D008563:Membrane Lipids; D003208:Concanavalin A