Binding of epidermal growth factor by human colon carcinoma cell (Caco-2) monolayers.
The objective of this study was to investigate whether Caco-2 cells bind and internalize epidermal growth factor (EGF). [125I]EGF was presented to the apical (AP) or basolateral (BL) side of Caco-2 monolayers, grown on microporous membranes, at different times in culture. At day 10, [125I]EGF binding (at 37 degrees C) to the BL membrane was 2-3 times greater than binding to the AP membrane. Of that [125I]EGF bound to the AP membrane 76% was internalized within 3 h while internalization from the BL membrane was 90%. At lower temperatures membrane-bound [125I]EGF increased while internalization decreased. At day 16, AP and BL binding decreased and then remained constant through day 25. [125I]EGF was bound to the BL membrane of 10 days old monolayers with a Kd of 0.67 nM. There was a single binding site whose numbers in the BL membrane was about 5500/cell.
Hidalgo
I J
IJ
Department of Pharmaceutical Chemistry, School of Pharmacy, University of Kansas, Lawrence 66045.
Kato
A
A
Borchardt
R T
RT
D002462:Cell Membrane / Q000378:metabolism; D003110:Colonic Neoplasms / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D014407:Tumor Cells, Cultured
D004815:Epidermal Growth Factor; D066246:ErbB Receptors