Journal article

RAPAMYCIN, WORTMANNIN, AND THE METHYLXANTHINE SQ20006 INACTIVATE P70(S6K) BY INDUCING DEPHOSPHORYLATION OF THE SAME SUBSET OF SITES

JW HAN, RB PEARSON, PB DENNIS, G THOMAS

JOURNAL OF BIOLOGICAL CHEMISTRY | AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC | Published : 1995

Abstract

Activation of p70s6k in cells stimulated with serum correlates with the phosphorylation of seven sites. Pretreatment of Swiss 3T3 cells with the immunosuppressant rapamycin blocks phosphorylation of four of these sites (Thr229, Thr389, Ser404, and Ser411), whereas phosphorylation proceeds in the remaining three sites (Ser418, Thr421, and Ser424). If rapamycin is added postserum stimulation, the pattern of phosphorylation is qualitatively similar except that Ser411 is still highly phosphorylated. The inhibitory effect of rapamycin on serum-induced p70s6k activation and the phosphorylation of Thr229, Thr389, Ser404, and Ser411 is rescued by FK506, providing further evidence that the inhibitory..

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