Table 1.

Quantification of Immunogold Labeling of Ultrathin Cryosections of COS Cells Transfected with GFP-tagged CLIMP-63 Constructs

	Gold particles per membrane length (arbitrary units) ± SD
	Nuclear envelope	ER	Nuclear envelope:ER
wt-GFP	0.06 ± 0.07	1.31 ± 0.52	1:34
Δlumen-GFP	0.29 ± 0.18	0.94 ± 0.36	1:4
GFP-Δcytoplasmic	0.06 ± 0.06	0.54 ± 0.39	1:12
Δ218–601	0.15 ± 0.15	0.62 ± 0.39	1:9

Labeling densities represent the means of 10 cells. Membrane lengths were measured by counting the number of intersections with a squared line lattice of 1 cm² at a magnification of 40,500×. Nuclear envelope/ER ratios were calculated per cell and represent the means of 10 cells.