Figure 9.

A point mutation that converts GFP to mGFP inhibits formation of OSER structures. (a) Immunoblot analysis of cells expressing unmutated or mGFP-Sec61γ lysates of equal amounts of cells untransfected (no DNA) or expressing either construct were loaded on the same gel and probed with anti-GFP or an antibody against native Sec61β as a control for equal loading. (b–d) Representative confocal micrographs of transiently transfected COS-7 cells expressing (b) mYFP-Sec61β, (c) mGFP-Sec61γ, and (d) C1(1-29)P450-mGFP reveal the absence of whorls, short karmellae, and loop structures. Other amorphous, often perinuclear, structures that are generally of much lower fluorescence intensity than cells expressing the unmutated GFP counterparts are visible. Bar, 5 μm.