Fig. 4. Sequence characterization of the Golgi-to-plasma membrane trafficking determinant in Kir2.1. (A) Primary sequence alignment of the identified trafficking determinant in Kir2.1 with the homologous sequence of Kir2.4. Non-conservative exchanges are in bold letters, the YXX consensus motif for adaptin binding is underlined. (B,C) Quantification of surface expression of Kir2.1 mutants and Kir2.4 mutants as indicated. Note that the Kir2.1 mutants in (B) show Golgi accumulation, indicating that the decrease in surface expression is not due to folding or ER export defects but to impaired post-Golgi transport. *Statistically significant when compared with respective controls (P<0.01; unpaired Student's t-test; see Materials and Methods).