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Dictionary > Cell structure > Endoplasmic reticulum

 Staining of endoplasmic reticulum in human cell line U-2 OS (HPA003901)
Scale bar represents 10µm

Endoplasmic reticulum

The endoplasmic reticulum is connected to the outer of the two nuclear membranes and consists of a series of interconnected membranes. It is usually divided into two parts: the smooth (sER) and the rough endoplasmic reticulum (rER), the latter being located closest to the nucleus. The rER has ribosomes attached to its cytoplasmic surface and is responsible for protein synthesis. The sER is involved in lipid and steroid synthesis. Lipids and correctly folded and assembled proteins are sent on to the Golgi apparatus for further processing and sorting. Another important task of the endoplasmic reticulum is the uptake and storage of calcium ions from the cytoplasm, as such will be released from the ER upon the receipt of certain extracellular signals.

Immunofluorescent staining

As the endoplasmic reticulum is consistent with the outer nuclear membrane, it is recognizable by a network-like staining of the cytoplasm and staining of the nuclear membrane. It is usually stronger close to the nucleus and weakens as it gets closer to the edges of the cell. The structure is a network of thin strands that intersect at regular intervals.

Examples IF

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