Fig. 5. PTP1B DA puncta do not co-localize with endocytic markers, but do co-localize with ER markers and require intact microtubules. PTP1B null cells stably expressing PTP1B DA were transfected with different endocytic markers: (A) the dominant-negative mutant GFP-dynamin K44A; (B) GFP-Rab 5; (C) GFP-Rab 7; (D) GFP-caveolin 1. Cells were fixed and stained with anti-PTP1B followed by a secondary antibody conjugated with Alexa Fluor 568. (E-G) PTP1B null cells were transfected with GFP-PTP1B DA (E) and stained with anti-calnexin antibody (F) followed by a secondary antibody conjugated with Alexa Fluor 568. The merged image is shown in G. PTP1B null cells were transfected with GFP-PTP1B DA in the absence (H) or presence (I) of Nocodazole (0.5 µM). After 20 hours, cells were fixed and stained with rhodamine-phalloidin. Note that the punctate structures (arrows in H) are not longer visible in the presence of nocodazole (I). Bars, (A-G) 20 µm; (H,I) 25 µm.