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Phosphatidylcholine (PC) synthesis in animal cells is generally controlled by cytidine 5'-triphosphate (CTP):phosphocholine cytidylyltransferase (CCT). This enzyme is amphitropic, that is, it can interconvert between a soluble inactive form and a membrane-bound active form. The membrane-binding domain of CCT is a long amphipathic alpha helix that responds(More)
The major site of phosphorylation of the epidermal growth factor (EGF) receptor after treatment of cells with EGF is threonine 669. Phosphorylation of this site is also associated with the transmodulation of the EGF receptor caused by platelet-derived growth factor and phorbol ester. A distinctive feature of the primary sequence surrounding threonine 669 is(More)
A growth factor-stimulated (MAP2-related) protein kinase, ERT, that phosphorylates the epidermal growth factor receptor at Thr669 has been purified from KB human tumor cells by Northwood and co-workers (Northwood, I. C., Gonzalez, F. A., Wartmann, M., Raden, D. L., and Davis, R. J. (1991) J. Biol. Chem. 266, 15266-15276). The ERT protein kinase has a(More)
A growth factor-stimulated protein kinase activity that phosphorylates the epidermal growth factor (EGF) receptor at Thr669 has been described (Countaway, J. L., Northwood, I. C., and Davis, R. J. (1989) J. Biol. Chem. 264, 10828-10835). Anion-exchange chromatography demonstrated that this protein kinase activity was accounted for by two enzymes. The first(More)
The transition from quiescence (G(0)) into the cell division cycle is marked by accelerated phospholipid turnover. We examined the rates of phosphatidylcholine (PC) synthesis and the activity, membrane affinity, and intracellular localization of the rate-limiting enzyme in the synthesis of PC, CTP:phosphocholine cytidylyltransferase (CT) during this(More)
Treatment of A431 human epidermoid carcinoma cells with 4-phorbol 12-myristate 13-acetate (PMA) causes an inhibition of the high affinity binding of epidermal growth factor (EGF) to cell surface receptors and an inhibition of the EGF receptor tyrosine protein kinase activity. The hypothesis that PMA controls EGF receptor function by regulating the(More)
The epidermal growth factor (EGF) receptor exists in a monomeric (170 kDa) form and in several aggregated states (360 kDa, greater than 500 kDa). The hypothesis that the oligomerization of the receptor is required for the stimulation of the kinase was tested by correlating the oligomeric state of the receptor with the protein kinase activity. EGF and(More)
Previous work identified a protein kinase activity that phosphorylates the epidermal growth factor (EGF) receptor at Thr669. An assay for this protein kinase activity present in homogenates prepared from A431 human epidermoid carcinoma cells was developed using a synthetic peptide substrate corresponding to residues 663-681 of the EGF receptor (peptide(More)
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