EGFP-PKD2 and ARF1-mRFP colocalize at the Golgi compartment. (A) HeLa cells coexpressing a wild-type EGFP-PKD2 and ARF1-mRFP were fixed followed by anti-TGN46/Alexa 647 immunostaining. The colocalization region is displayed in the zoom area. GFP-PKD1 and GFP-PKD3 colocalize with ARF1-mRFP. (B) HeLa cells coexpressing a wild-type GFP-PKD1 and ARF1-mRFP. (C) HeLa cells coexpressing a wild-type GFP-PKD3 and ARF1-mRFP. (D) HeLa cells expressing ARF1-mRFP were fixed followed by PKD2-antibody/Alexa 488 immunostaining. The colocalization region is displayed in the zoom area. Class I and II ARF proteins specifically regulate the TGN localization of PKD2. HeLa cells overexpressing an empty HA-tag vector (E), ARF1-T31N-HA (F), ARF3-T31N-HA (G), ARF4-T31N-HA (H), ARF5-T31N-HA (I), or ARF6-T27N-HA (J) were fixed followed by HA-antibody/Alexa 594 and PKD2-antibody/Alexa488 immunostaining. Transfected cells are indicated by arrows. Bars, 20 μm. (K) The histogram shows the quantification of the average fluorescence intensity of endogenous PKD2 for at least 40 cells around the perinuclear area in the cells overexpressing various ARF-inactive mutants. Data are means ± SEM of two independent experiments.