Figure 5.

Mutation of tryptophans in TM1 of MARCH9 causes moderate defects, but mutation of a glycophorin A-like motif does not. A, sequences of mutants analyzed in this figure. Red bold font indicates substituted amino acids. B–E, 293T cells stably expressing human CD4 were transduced with the indicated lentiviral constructs, and surface levels of HLA-A2 (B and D) and CD4 (C and E) were measured after 48 h culture with or without dox as in Fig. 1. Dashed lines indicate mean substrate level remaining on dox-treated cells expressing control WT (lower) and RING mutant W143A (upper) MARCH9. Unpaired t test: ns, not significant; *, p < 0.05; **, p < 0.02; ***, p < 0.001; ****, p < 0.0001.