The C-terminal domain of HookA is capable of interacting with early endosomes. (A) Two examples showing that the C-HookA–GFP signals are concentrated at the hyphal tip where mCherry-RabA–marked early endosomes accumulate and the GFP and mCherry signals largely overlap (100% hyphal tips that show the concentrated GFP signals show the mCherry-RabA accumulation; n = 50). (B) A Western blot showing that the protein level of C-HookA–GFP expressed under the gpdA promoter (gpdA-C-HookA–GFP) is much higher than that expressed under the endogenous hookA promoter (C-HookA–GFP). The proteins were pulled down by the anti-GFP antibody, and the Western blot was probed by the anti-GFP antibody. Quantitation of the Western blots suggests that the level of gpdA-C-HookA–GFP is significantly higher than that of C-HookA–GFP (P < 0.005, n = 3). If we set the values of C-HookA–GFP as 1, the mean ± SD value of gpdA-C-HookA–GFP is 3.1 ± 0.4. This is likely to be an underestimate of the gpdA-C-HookA–GFP protein level as there seems to be a lot of degradation products, which are hard to include in the measurements. (C) Phenotypic analysis of the diploids showing that overexpression of C-HookA (gpdA-C-HookA–GFP) in the wild-type background produced a dominant-negative phenotype in early endosome distribution. Bars, 5 µm.