Schematic diagram of dileucine internalization motif. The extracellular (EX), transmembrane (TM) and intracellular (ID) domains are indicated for gp130 and the wild-type (WT) and mutant ▵716 G-CSFR forms. A dileucine motif (underlined) that modulates ligand internalization and receptor expression localizes to the distal region of box 3 in gp130. An identical motif is present in the WT G-CSFR (underlined). Mutations in the critical region in patients with SCN/AML as in the ▵716 mutation result in the introduction of a premature stop codon (STOP) and deletion of the carboxy-terminal tail of the G-CSFR (diagonal lines) within which lies the dileucine motif (underlined).