C-terminal region is required for p115 function. (A) Diagram of full-length and C-terminal p115 mutants. (B,C) HeLa cells transfected with GFP-tagged p115/1-959 or p115/1-820 (B) or Myc-tagged p115/1-934 or p115ΔCC4 (C) for 18 hours were lysed and the lysates were immunoblotted with anti-p115 and anti-β-tubulin antibodies (B) or with anti-Myc and anti-β-tubulin antibodies (C). All constructs express the appropriate proteins. (D,E) HeLa cells transfected with GFP-p115/1-820 or Myc-p115/1-934 for 18 hours were analyzed by immunofluorescence with indicated antibodies. Expression of p115/1-820 disrupts Golgi ribbon (D, cell marked with arrowhead). Expression of p115/1-934 has no visible effect on Golgi architecture (E, cell marked with arrowhead). Scale bars: 10 µm. (F,G) HeLa cells silenced with anti-p115 siRNA for 3 days were transfected with GFP-p115/1-820 or Myc-p115/1-934 for 18 hours, and analyzed by immunofluorescence with indicated antibodies. p115 depletion fragments the Golgi (cell marked with *). Expression of p115/1-820 does not reverse Golgi disruption (F, cell marked with arrowhead). Expression of p115/1-934 reverses Golgi disruption (G, cell marked with arrowhead). Scale bars: 10 µm.