Sigma Receptors
Signaling Pathways

Author: Gianpiero Pescarmona
Date: 28/12/2019



A short protein description with the molecular wheight, isoforms, etc...
Use, when available, the link to Wikipedia (Es Trypsin)

External links not available on Wikipedia have to be added here




When relevant for the function

  • Primary structure
  • Secondary structure
  • Tertiary structure
  • Quaternary structure

Protein Aminoacids Percentage
The Protein Aminoacids Percentage gives useful information on the local environment and the metabolic status of the cell (starvation, lack of essential AA, hypoxia)

Protein Aminoacids Percentage (Width 700 px)


mRNA synthesis
protein synthesis

post-translational modifications


cellular localization,
biological function

  • Enzymes
BRENDA - The Comprehensive Enzyme Information System"URL":
KEGG Pathways"URL":
Human Metabolome Database"URL":
  • Cell signaling and Ligand transport
  • Structural proteins



Sigma 1-type opioid receptor (Sigma1R) (Sigma1-receptor) (hSigmaR1) (SIG-1R) (SR31747-binding protein) (SR-BP) (Aging-associated gene 8 protein)

A protein with high Trp and Phen, Low Tyr

1. FUNCTION: Functions in lipid transport from the endoplasmic reticulum and is involved in a wide array of cellular functions probably through regulation of the biogenesis of lipid microdomains at the plasma membrane. Involved in the regulation of different receptors it plays a role in BDNF signaling and EGF signaling. Also regulates ion channels like the potassium channel and could modulate neurotransmitter release. Plays a role in calcium signaling through modulation together with ANK2 of the ITP3R-dependent calcium efflux at the endoplasmic reticulum. Plays a role in several other cell functions including proliferation, survival and death. Originally identified for its ability to bind various psychoactive drugs it is involved in learning processes, memory and mood alteration.
2. SUBCELLULAR LOCATION: Nucleus inner membrane. Nucleus outer membrane. Endoplasmic reticulum membrane. Lipid droplet. Cell junction. Cell membrane. Cell projection, growth cone. Note=Targeted to lipid droplets, cholesterol and galactosylceramide-enriched domains of the endoplasmic reticulum. Enriched at cell-cell communication regions, growth cone and postsynaptic structures. Localization is modulated by ligand- binding.
3. ALTERNATIVE PRODUCTS: Event=Alternative splicing; Named isoforms=5; Name=1; IsoId=Q99720-1; Sequence=Displayed; Name=2; IsoId=Q99720-2; Sequence=VSP_021982; Name=3; Synonyms=Sigma-R1A; IsoId=Q99720-3; Sequence=VSP_021986; Name=4; IsoId=Q99720-4; Sequence=VSP_021984, VSP_021985; Name=5; IsoId=Q99720-5; Sequence=VSP_021981, VSP_021983; Note=No experimental confirmation available;
4. TISSUE SPECIFICITY: Widely expressed with higher expression in liver, colon, prostate, placenta, small intestine, heart and pancreas. Expressed in the retina by retinal pigment epithelial cells.
5. MISCELLANEOUS: Depletion of OPRS1 by RNAi inhibits growth and survival signaling cascades and induces cell death. The OSPR1 antagonist rimcazole produces the same effect.
6. SIMILARITY: Belongs to the ERG2 family.
7. WEB RESOURCE: Name=Wikipedia; Note=Sigma-1 receptor entry; URL=

Cell localization and function

Several studies demonstrated that both type-1 and –2 sigma receptors regulate Ca2+ efflux from the endoplasmic reticulum.

Cell localization (from The Sigma Receptor: Evolution of the Concept in Neuropsychopharmacology 2005

The Roles of Intracellular Chaperone Proteins, Sigma Receptors, in Parkinson’s Disease (PD) and Major Depressive Disorder (MDD), 2019

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