The network of folded membranes that comprises the endoplasmic reticulum (ER) in all eukaryotic cells constitutes greater than half of the total membrane content in the average animal cell. The branching tubules and flattened sacs of the ER come in two forms: membrane bound by ribosomes (rough ER) or unbound by ribosomes (smooth ER). The ER has a central role in lipid and protein synthesis, protein chaperoning and folding, and calcium homeostasis. Three distinct Molecular Probes® technologies are routinely used for ER imaging in live or fixed cells.

CellLight® reagents for ER

Use CellLight® reagents when you want to label the ER in live cells to follow the dynamics of cellular behavior. CellLight® proteins can be multiplexed with other fluorescent probes for analysis in live cells or after fixation for colocalization studies. These ready-to-use constructs express fluorescent proteins with ER-retention signals from calreticulin (1.8 kDa, N-term), a resident protein of the ER lumen, and KDEL (0.5 kDa, C-term). Introducing CellLight® reagents involves a simple transfection step, and they work like cell stains with minimal toxicity or chemical disruption.

CellLight® ER-RFP Enlarge image

ER-Tracker™ dyes for live cells

ER-Tracker™ dyes are cell-permeant live-cell stains that are highly selective for the ER. When cells are stained using the protocol provided, the staining pattern is partially retained after fixation with formaldehyde. The respective BODIPY® dyes are targeted using glibenclamide, which binds to the sulfonylurea receptors of ATP-sensitive K+ channels that are prominent on ER. Note: The pharmacological activity of glibenclamide could potentially affect ER function.

ER-Tracker™ GreenEnlarge image

Conjugates for fixed-cell staining

The ER can be labeled in fixed cells using fluorescent conjugates of lectins such as concanavalin A, or antibodies directed against ER-associated proteins such as disulfide isomerase (PDI). We offer concanavalin A conjugated to Alexa Fluor® 594, and an ER-labeling kit with an anti-PDI primary and Alexa Fluor® 488–labeled secondary antibody. The SelectFX® kit also provides cell fixative and permeabilization reagents.

Alexa Fluor® 488 concanavalin AEnlarge image
Selection guides
 
Readout
 Expression of fluorescent fusion protein
Target
 Protein retained in ER lumen
Common filter set
FITC
TRITC
Labels
GFP
RFP
Ex/Em (nm)
488/520
555/584
Signal-to-noise ratio
Photostability
Multiplexing
Yes
Yes
Live cells
Yes
Yes
Fixed cells
No
No
Fixable
Yes
Yes
Platform
 Imaging
 Imaging
Format
1 mL
1 mL
Cat. No.
 
Readout
 Live cell ER staining
Target
 Binds to K+ channels in ER
Common filter set
FITC
Texas Red®
Labels
BODIPY® FL
BODIPY® TR
Ex/Em (nm)
504/511
587/615
Signal-to-noise ratio
Photostability
Multiplexing
Yes
Yes
Live cells
Yes
Yes
Fixed cells
No
No
Fixable
Yes
Yes
Platform
 Imaging
Imaging 
Format
100 μg
100 μg
Cat. No.
 
Readout
 Fixed-cell ER staining
Target
ER-associated PDI
α-glucopyranosyl residues in ER
Common filter set
Texas Red®
FITC
Labels
Alexa Fluor® 594
Alexa Fluor® 488
Ex/Em (nm)
561/594
496/519
Signal-to-noise ratio
Photostability
Multiplexing
Yes
Yes
Live cells
No
No
Fixed cells
Yes
Yes
Fixable
No
No
Platform
Imaging
Imaging
Format
5 mg
1 set
Cat. No.
For Research Use Only. Not for use in diagnostic procedures.