Schematic maps of Mpl constructs.

The top drawing depicts the 625-amino acid wild-type murine Mpl with the extracellular, intracellular, and transmembrane (TM; cross-hatch) domains indicated. The N-terminal FLAG epitope is located immediately downstream of the leader sequence. Intracellular domains of the 5 constructs used in this report are schematized showing the location of Box1, Box2, and the 5 intracellular tyrosines. Mpl-Δ7 is missing the 10 intracellular residues (505-514) immediately adjacent to the cell membrane. Mpl-Δ50 lacks the 50 C-terminal amino acids, residues 576 to 625.