Table 1.

Effect of added Tat protein on incorporation of ⁷⁵Se by Jurkat T cells

Incubation with 75Se, hr	Total 75Se present/0.6 ml of extract
	Control T cells,		Tat-treated T cells,
	cpm × 106	%	cpm × 106	%
28	0.3	0.5	1.02	1.73
50	1.2	2.05	2.85	4.85

Jurkat T cells were propagated in 6-ml cultures containing RPMI medium 1640 with 10% fetal bovine serum and either maltose-binding protein (42 kDa), 10 μg, (controls) or maltose-binding-Tat fusion protein (52 kDa), 10 μg, (Tat-treated cells) for 24 or 48 hr at 37°C in a CO₂ incubator. Then 58.8 × 10⁶ cpm ⁷⁵SeO₃²⁻ (ca. 3 nmoles; Los Alamos National Laboratory, NM) were added to each 6-ml culture and incubation was continued for 28 hr (24-hr culture) or 50 hr (48-hr culture). Cells were harvested, washed twice, and suspended in SDS/PAGE sample buffer with mercaptoethanol as described in Materials and Methods. Extracts (0.6 ml) were heated at 100°C for 10 min.