FIG. 3.

Numb PTB domain mutations predicted to disrupt the interaction with the NPXpY motif do not affect the interaction with Nak. (A) The mutation R171N (substitution of arginine with asparagine at position 171) slightly reduces the interaction between Numb-PTB and GST-Nak(1385–1490) (the middle three lanes). The mutation S148A (substitution of serine with alanine at position 148) does not affect the interaction at all (the last three lanes). The first three lanes are wild-type controls as shown in Fig. 2B. (B) Two-hybrid assay for the interactions between Numb-PTB (wild type and two mutants) and Nak(1385–1490). Both mutants, R171N and S148A, yielded LacZ activities similar to that of the wild-type control.