Treatment of Nef transfected T cells with TPCK or TLCK altered the mobility of Nef on SDS-PAGE. (A) Anti-Nef immunoblotting of Nef proteins from TPCK, TLCK or Z-FA-FMK treated cells. JTAg cells were transfected with Nef NA7 (upper panel), Nef NL4-3 (middle panel) or NA7 (G2G3/AA), treated with TPCK, TLCK or Z-FA-FMK for 30 min as indicated. The whole cell lysates were immunoblotted with anti-Nef. Arrows indicate the faster (F) or slower (S) migrated Nef proteins. (B) Structures of TPCK, TLCK and Z-FA-FMK. The boxed atoms are the alkylating groups reacting with specific His or Cys residues in substrate proteins.