Table 1.

Quantification of colocalization of ssYFP with subcellular compartment markers

Marker	Compartment	ssYFP Colocalization, %	PCC
Golgin-97	TGN	60.9±3 (34.9±0.5)	0.30±0.03 (0.48±0.02)
Alexa 555-dextran	Endocytotic vesicles	3.8±2	0.05±0.02
LysoTracker	Late endosomes and lysosomes	3.5±2	0.03±0.01
Rab11	Recycling endosomes	28.2±4 (17.2±4)	0.09±0.02 (0.21±0.01)

Values are means ± SE (n = 3). 3-Dimensional image stacks of immunostained secreted soluble yellow fluorescent protein (ssYFP) colabeled with the listed organelle markers were analyzed for each condition using Volocity's (Improvision) colocalization function (see Fig. 1 for representative image slices). Colocalization values are reported as percentage of above-threshold pixels in ssYFP channel that overlapped above-threshold pixels in compartment marker channel. Values in parentheses represent colocalization of native ssYFP fluorescence and the given compartment marker. Pearson's correlation coefficient (PCC) is an indication of colocalization significance, where higher values correspond to a greater significance (4). TGN, trans-Golgi network.