Organelle · tubular network
Smooth endoplasmic reticulum
Lipid kitchen & detox unit
In view
The tubules sway, and every so often a new one grows out, links up with the net and later lets go again: the ER network is constantly remodelling itself.
The ribosome-free part of the ER is a web of tubes meeting at three-way junctions. It makes most of the cell’s membrane lipids, and in hormone-producing cells it makes steroids.
In liver cells it is packed with cytochrome P450 enzymes that neutralise drugs and toxins. In every cell it serves as a calcium reservoir.
- Makes
- Lipids · steroids
- Detox
- Cytochrome P450
- Ca²⁺ inside
- ≈ 2,500× the cytosol
- In muscle
- Sarcoplasmic reticulum
Did you know?
Dose a liver with phenobarbital for a few days and its smooth ER multiplies until it dominates the cytoplasm, boosting detox capacity.
Sources
- Increased spatiotemporal resolution reveals highly dynamic dense tubular matrices in the peripheral ER · Nixon-Abell et al. 2016 · Science
- Dynamic behavior of endoplasmic reticulum in living cells · Lee & Chen 1988 · Cell
- A class of dynamin-like GTPases involved in the generation of the tubular ER network · Hu et al. 2009 · Cell
- The endoplasmic reticulum: structure, function and response to cellular signaling · Schwarz & Blower 2016 · Cell Mol Life Sci
- How big is the endoplasmic reticulum of cells? · Milo & Phillips · Cell Biology by the Numbers
- Syntaxin 17 is abundant in steroidogenic cells and implicated in smooth endoplasmic reticulum membrane dynamics · Steegmaier et al. 2000 · Mol Biol Cell
- Correlated morphometric and biochemical studies on the liver cell. II. Effects of phenobarbital on rat hepatocytes · Stäubli et al. 1969 · J Cell Biol
- Studies on the resolution of subcellular free calcium concentrations: a technological advance. Focus on "detection of differentially regulated subsarcolemmal calcium signals activated by vasoactive agonists in rat pulmonary artery smooth muscle cells" · Xu et al. 2014 · Am J Physiol Cell Physiol
- Intracellular Membrane Contact Sites in Skeletal Muscle Cells · Serano et al. 2025 · Membranes (Basel)