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. 2015 Aug 31;290(43):26270–26281. doi: 10.1074/jbc.M115.684746

FIGURE 4.

FIGURE 4.

Akt phosphorylation depends on the PDZ-binding domain of Tax1. A, P-AktSer-473 (P-AktS473) and total Akt levels were determined in IL-2/phytohemagglutinin-stimulated PBMCs as compared with HTLV-1-immortalized cell lines Hut102 and MT4. The ratios of P-AktSer-473 to total Akt are shown as measured by densitometry. Immunoblots show the expression of Tax and Env-Tax fusion proteins in these cell lines, as well as GSK3β phosphorylation, and levels of PHLPP, PTEN, and actin. B, Jurkat cells and Tet-On Tax1 Jurkat cells were grown in the presence or absence of doxycycline (Dox) for 48 h and then stimulated for 0, 15, or 30 min on CD3/CD28-coated plates. C, Jurkat cells were transfected with empty vector or expression plasmids for STax1, STax2, or STax1ΔPBM. The ratios of P-AktThr-308 (P-AktT308) and P-AktSer-473 (P-AktS473) to total Akt are shown as measured by densitometry. Combined results of four separate experiments revealed statistically significant differences between P-AktThr-308/total Akt ratio for Jurkat cells expressing STax1 versus STax1ΔPBM (p = 0.033). D, 293T cells were transfected with empty vector or expression plasmids for STax1, STax1ΔPBM, or STax2. The ratios of P-AktThr-308 and P-AktSer-473 to total Akt are shown as measured by densitometry.