Endoplasmic Reticulum (ER) Structure
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.
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.
- Select ER-Tracker™ dyes
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.
- Select conjugates for fixed cells
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. |
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. |
Resources
Research toolsMolecular Probes® Handbook |
BioProbes® 70 Journal articleRelated instruments and applications |