title: Epidermal growth factor binding and stimulation of inositol trisphosphate production in basolateral membranes from dog kidney.
abstract: To ascertain whether epidermal growth factor (EGF) receptors are present in proximal tubular basolateral membranes from dog kidney and whether the growth factor activates phospholipase C at this site, we measured binding of 125I-EGF in isolated membranes and determined whether incubation of the membranes with EGF results in generation of inositol trisphosphate. Specific binding of 125I-EGF to basolateral membranes was observed that was half-maximally inhibited by approximately 7 x 10(-10) M EGF. The specific binding capacity of basolateral membranes for EGF averaged 45.9 fmol/mg protein. 125I-EGF was crosslinked to 2 proteins in basolateral membranes with M(r)s of 170,000 and 150,000. EGF stimulated phosphorylation of a 170,000 M(r) protein. Incubation of basolateral membranes with EGF stimulated inositol trisphosphate production in a concentration-dependent manner. We conclude that EGF activates a phospholipase C activity that cleaves phosphatidylinositol 4,5-bisphosphate within the basolateral membrane.
authors: Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
authors: S A
authors: SA
authors: Rogers
authors: M R
authors: MR
authors: Hammerman
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D004285:Dogs; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism*; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D010766:Phosphorylation; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D004815:Epidermal Growth Factor; D015544:Inositol 1,4,5-Trisphosphate; D066246:ErbB Receptors; D010738:Type C Phospholipases