Fig. 9. Alfy localizes to a novel filamentous structure. (A) HeLa cells grown on gridded coverslips were starved in HBSS for 45 minutes, fixed and labelled with anti-Alfy to detect cells with Alfy-positive structures (A,B, arrowheads). The same cells were thereafter localized on EM using the grid on the coverslip (B). The Alfy-positive structures detected by immunofluorescence (A) could also be detected at the EM level (B), making it possible to study these structures at a higher resolution (D corresponds to structure 2 and C corresponds to structure 1). This showed that Alfy localizes to a novel filamentous structure (C,D, arrows) that, in some cases, localized close to rough ER membranes (C,D, arrowheads). Occasionally, we observed double-membrane structures embedded within the Alfy-positive structures (E, arrows). The filamentous nature of Alfy structures becomes more evident at a higher magnification (F). Abbreviation: Nu, nucleus.