Fig. 6. Cys306 is part of a transglutaminase domain that forms the active site of N-glycanase. [³⁵S]methionine-labeled TCRα was incubated either with buffer alone (lane 1) or with [³⁵S]methionine-labeled extracts obtained from HEK-293 cells that were mock transfected, (lane 2), from transfectants expressing PNG1–GFP (lanes 3–5) or from transfectants expressing PNG^Ala306–GFP (lane 6). NEM or DTT was added to the incubations as indicated. After the incubations, immunoprecipitations with anti-TCRα and anti-GFP antibodies were performed simultaneously.