FIGURE 6.

Dileucine motif on R1a determines the rate of internalization. A, GIRK cells expressing R1a^{BBS-ASA,L889A,L890A} (top) or R1a^BBS-ASAR2ΔCT (bottom) were incubated in 3 μg/ml BTX-AF555 for 10 min at room temperature and imaged over 0–60 min at room temperature. Scale bar, 5 μm. B, rates of constitutive internalization for R2^BBS, R1a^BBSR2, R1a^{BBS-ASA,L889A,L890A}, R1a^BBS-ASA, and R1a^BBS-ASAR2ΔCT receptors (n = 6). C, decay time constants for the surface membrane fluorescence for the subunits indicated, where R1a^{BBS-ASA-L889A,L890A} = R1a^BBS-ASA-AA. D, extent of internalization for the subunits indicated. *, p < 0.05; **, p < 0.01; ***, p < 0.001, one-way analysis of variance. Error bars, S.E.