Epidermal growth factor induces the accumulation of calpactin II on the cell surface during membrane ruffling.
Confluent and proliferatively quiescent T51B rat liver epithelial cells provide a cellular model for the study of epidermal growth factor (EGF) effects in non-neoplastic cells. Immunoreactive calpactin II, a well-known substrate for EGF-receptor kinase, was found predominantly in the cytosol, although a second immunoreactive pool was found in a Triton X-100-extractable membrane fraction. Stimulation with EGF resulted in a rapid and transient (2-5 min) formation of ruffles at the cell surface and at the cell-cell contacts. Both calpactin II and filamentous actin were found co-localized at the membrane ruffles. Immunoprecipitations of membrane-bound calpactin II from 32P-labeled cells indicate a transient EGF-dependent phosphorylation of calpactin II correlating with membrane ruffling. These results suggest a temporal (2-5 min) function for calpactin II at the plasma membrane during the EGF-induced mitogenesis of T51B cells.
Campos-Gonzalez
R
R
Cancer Research Center of Hawaii, University of Hawaii, Honolulu.
Kanemitsu
M
M
Boynton
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AL
D000199:Actins / Q000032:analysis; D000818:Animals; D017302:Annexins; D002135:Calcium-Binding Proteins / Q000032:analysis* / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000032:analysis* / Q000187:drug effects / Q000648:ultrastructure; D003600:Cytosol / Q000032:analysis; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005455:Fluorescent Antibody Technique; D008565:Membrane Proteins / Q000032:analysis* / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats
D000199:Actins; D017302:Annexins; D002135:Calcium-Binding Proteins; D008565:Membrane Proteins; D004815:Epidermal Growth Factor