Immunofluorescent images of formaldehyde-fixed cell lines are shown. Three different organelle markers are displayed as different channels in the multicolor images - nucleus stained in blue, microtubules in red and ER in yellow. The various cell structures that are demonstrated are always shown in the green channel using an antibody found in the Human Protein Atlas. The antibody id is linked to the corresponding Cell Atlas protein page. By using the "toggle channels"-buttons, the different channels can be turned on and off. Most cell structures can be highlighted in the cell illustration by hovering over them with the exception of the aggresome. Cytoplasmic bodies are highlighted as cytosol; cytokinetic bridge, midbody, midbody ring and mitotic spindle are highlighted as microtubules, cell junctions are highlighted as plasma membrane and nucleus is highlighted as nucleoplasm.
Staining of endoplasmic reticulum in human cell line U-2 OS (HPA009696)
Scale bar represents 10µm
The endoplasmic reticulum (ER) is contiguous to the outer nuclear membrane and consists of a membraneous network that is divided into two parts: the rough (rER) and the smooth endoplasmic reticulum (sER). The rER has ribosomes attached to its cytoplasmic surface and is responsible for protein synthesis. Synthesized proteins are controlled for their quality in the rER – misfolded proteins are degraded while correctly assembled proteins can be sent to the Golgi apparatus. The sER is involved in the synthesis of different lipid classes. In addition, the ER is a major storage site for intracellular calcium ions. It is maintaining the Ca2+ homeostasis in the cell by a regulated release and uptake of ions from the cytosol.
The ER is recognizable by a network-like staining in the cytoplasm. The network consists of thin tubular strands at the edges of the cell and is denser close to the nucleus. The ER also often shows a similar staining pattern as the nuclear membrane, as both are contiguous to each other.