Figure 7.
An ER-retained Caveolin-1 partitions into tubules. (A) Predicted topology of GFP-tagged Caveolin-1 with a C-terminal ER retention signal (KKKAE). (B) GFP-Cav1ER (first column, green) expressed in Cos-7 cells localizes to the tubular ER and edges of cisternae (zoom image, white arrow) whereas normal ER resident ER membrane protein, mCherry-Sec61β (second column, red), localizes to all ER sub-domains, including the NE and peripheral ER cisternae. (C) Model of GFP-Cav1ERTM with lengthened TM domain. (D) Colocalization images as in (B) for construct in (C) showing localization of GFP-Cav1ERTM at the NE. (E) Model of monomeric ER-retained caveolin, GFP-Cav1ERC66A construct with mutations changing residues 66–70 to alanines (zoom image). (F) Colocalization images as in (B) for construct in (E) showing localization of GFP-Cav1ERC66A at the NE (zoom image). Scale bar = 10μm.