The STIM1 gene provides instructions for making a protein called stromal interaction molecule 1 (STIM1). The STIM1 protein is involved in controlling the entry of positively charged calcium atoms (calcium ions) into cells when levels of the ions are low, specifically through channels called calcium-release activated calcium (CRAC) channels. The flow of calcium ions through CRAC channels triggers signaling within cells that plays a role in many cellular functions including control of gene activity, cell growth and division, and immune function.
STIM1 is found in the membrane of a cellular structure called the endoplasmic reticulum (ER), which, among other functions, stores calcium in cells. STIM1 recognizes when calcium levels in the ER are low and stimulates changes in the cell that allow STIM1 to attach (bind) to a protein called ORAI1 in the cell membrane. This protein, which is part of the CRAC channel, forms a hole (pore) in the cell membrane through which calcium ions can flow. STIM1 binding triggers the flow of calcium ions into the cell through the channel. STIM1 also likely plays a role in the process that stops the flow of calcium ions when enough calcium has entered.
STIM1 is also found in the sarcoplasmic reticulum, a structure similar to the ER that is found in muscle cells. This structure plays a major role in muscle contraction and relaxation by storing and releasing calcium ions. The STIM1 protein is thought to help replenish calcium stores in the sarcoplasmic reticulum through CRAC channels. It may also be involved in the release of calcium ions from the sarcoplasmic reticulum, which stimulates muscle contraction.
Health Conditions Related to Genetic Changes
A mutation in the STIM1 gene causes Stormorken syndrome, a rare condition characterized by a low number of blood cells called platelets (thrombocytopenia) and consequent bleeding problems, a muscle disorder called tubular aggregate myopathy (described below), and other abnormalities.
The mutation involved in this condition changes a single protein building block (amino acid) in the STIM1 protein, replacing the amino acid arginine with the amino acid tryptophan at protein position 304 (written as Arg304Trp or R304W). This change occurs in a region of the protein that is thought to be involved in keeping it turned off when calcium ion levels are high. As a result of this change, the altered STIM1 protein is constantly turned on (constitutively active), continually stimulating calcium ion entry through CRAC channels regardless of ion levels in the ER.
Because the genetic change enhances the activity of the protein, it is described as a "gain-of-function" mutation. Researchers suggest that the abnormal ion flow in platelets causes the cells to break down earlier than usual, leading to thrombocytopenia and bleeding problems in people with Stormorken syndrome. It is unknown how constitutively active STIM1 leads to the other features of the disorder.More About This Health Condition
Tubular aggregate myopathy
At least five gain-of-function mutations cause tubular aggregate myopathy without the other features of Stormorken syndrome (described above). In this disorder, proteins build up abnormally in muscle cells, forming clumps of tube-like structures called tubular aggregates. Tubular aggregate myopathy causes muscle pain, cramping, or weakness that worsens over time.
The mutations involved in this condition change single amino acids in STIM1, specifically in the region of the protein used for sensing calcium ion levels. Like the gain-of-function mutation that causes Stormorken syndrome, these mutations lead to production of a constitutively active STIM1 protein that continually stimulates calcium ion flow through CRAC channels.
It is unclear how abnormal ion flow leads to tubular aggregate myopathy. Evidence suggests that the tubular aggregates are composed of proteins that are normally part of the sarcoplasmic reticulum. Although the mechanism is unknown, some researchers speculate that the aggregates are the result of uncontrolled calcium levels in muscle cells, possibly due to abnormal STIM1 activity.
Researchers are not sure why another gain-of-function mutation causes the additional signs and symptoms of Stormorken syndrome.More About This Health Condition
At least three mutations in the STIM1 gene cause an immune system disorder called primary immunodeficiency 10. Because of immune system problems, individuals with this condition have recurrent infections that can be life-threatening. The mutations that cause primary immunodeficiency 10 are known as "loss-of-function" mutations because they reduce or eliminate the function of the STIM1 protein. Without stimulation by STIM1, calcium ion flow through CRAC channels is impaired, which hinders the ability of immune system cells to fight infections.
Other Names for This Gene
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
- Bohm J, Chevessier F, Maues De Paula A, Koch C, Attarian S, Feger C, Hantai D, Laforet P, Ghorab K, Vallat JM, Fardeau M, Figarella-Branger D, Pouget J, Romero NB, Koch M, Ebel C, Levy N, Krahn M, Eymard B, Bartoli M, Laporte J. Constitutive activation of the calcium sensor STIM1 causes tubular-aggregate myopathy. Am J Hum Genet. 2013 Feb 7;92(2):271-8. doi: 10.1016/j.ajhg.2012.12.007. Epub 2013 Jan 17. Citation on PubMed or Free article on PubMed Central
- Chevessier F, Bauche-Godard S, Leroy JP, Koenig J, Paturneau-Jouas M, Eymard B, Hantai D, Verdiere-Sahuque M. The origin of tubular aggregates in human myopathies. J Pathol. 2005 Nov;207(3):313-23. doi: 10.1002/path.1832. Citation on PubMed
- Cottam NP, Ungar D. Retrograde vesicle transport in the Golgi. Protoplasma. 2012 Oct;249(4):943-55. doi: 10.1007/s00709-011-0361-7. Epub 2011 Dec 12. Citation on PubMed
- Hedberg C, Niceta M, Fattori F, Lindvall B, Ciolfi A, D'Amico A, Tasca G, Petrini S, Tulinius M, Tartaglia M, Oldfors A, Bertini E. Childhood onset tubular aggregate myopathy associated with de novo STIM1 mutations. J Neurol. 2014 May;261(5):870-6. doi: 10.1007/s00415-014-7287-x. Epub 2014 Feb 26. Citation on PubMed
- Kilch T, Alansary D, Peglow M, Dorr K, Rychkov G, Rieger H, Peinelt C, Niemeyer BA. Mutations of the Ca2+-sensing stromal interaction molecule STIM1 regulate Ca2+ influx by altered oligomerization of STIM1 and by destabilization of the Ca2+ channel Orai1. J Biol Chem. 2013 Jan 18;288(3):1653-64. doi: 10.1074/jbc.M112.417246. Epub 2012 Dec 4. Citation on PubMed or Free article on PubMed Central
- Lee KJ, Hyun C, Woo JS, Park CS, Kim DH, Lee EH. Stromal interaction molecule 1 (STIM1) regulates sarcoplasmic/endoplasmic reticulum Ca(2)(+)-ATPase 1a (SERCA1a) in skeletal muscle. Pflugers Arch. 2014 May;466(5):987-1001. doi: 10.1007/s00424-013-1361-6. Citation on PubMed
- Lee KJ, Woo JS, Hwang JH, Hyun C, Cho CH, Kim DH, Lee EH. STIM1 negatively regulates Ca(2)(+) release from the sarcoplasmic reticulum in skeletal myotubes. Biochem J. 2013 Jul 15;453(2):187-200. doi: 10.1042/BJ20130178. Citation on PubMed
- Misceo D, Holmgren A, Louch WE, Holme PA, Mizobuchi M, Morales RJ, De Paula AM, Stray-Pedersen A, Lyle R, Dalhus B, Christensen G, Stormorken H, Tjonnfjord GE, Frengen E. A dominant STIM1 mutation causes Stormorken syndrome. Hum Mutat. 2014 May;35(5):556-64. doi: 10.1002/humu.22544. Epub 2014 Apr 9. Citation on PubMed
- Nesin V, Wiley G, Kousi M, Ong EC, Lehmann T, Nicholl DJ, Suri M, Shahrizaila N, Katsanis N, Gaffney PM, Wierenga KJ, Tsiokas L. Activating mutations in STIM1 and ORAI1 cause overlapping syndromes of tubular myopathy and congenital miosis. Proc Natl Acad Sci U S A. 2014 Mar 18;111(11):4197-202. doi: 10.1073/pnas.1312520111. Epub 2014 Mar 3. Citation on PubMed or Free article on PubMed Central
- Parekh AB. Local Ca2+ influx through CRAC channels activates temporally and spatially distinct cellular responses. Acta Physiol (Oxf). 2009 Jan;195(1):29-35. doi: 10.1111/j.1748-1716.2008.01919.x. Epub 2008 Oct 28. Citation on PubMed
- Picard C, McCarl CA, Papolos A, Khalil S, Luthy K, Hivroz C, LeDeist F, Rieux-Laucat F, Rechavi G, Rao A, Fischer A, Feske S. STIM1 mutation associated with a syndrome of immunodeficiency and autoimmunity. N Engl J Med. 2009 May 7;360(19):1971-80. doi: 10.1056/NEJMoa0900082. Citation on PubMed or Free article on PubMed Central
- Prakriya M. Store-operated Orai channels: structure and function. Curr Top Membr. 2013;71:1-32. doi: 10.1016/B978-0-12-407870-3.00001-9. Citation on PubMed or Free article on PubMed Central
- Zhou Y, Meraner P, Kwon HT, Machnes D, Oh-hora M, Zimmer J, Huang Y, Stura A, Rao A, Hogan PG. STIM1 gates the store-operated calcium channel ORAI1 in vitro. Nat Struct Mol Biol. 2010 Jan;17(1):112-6. doi: 10.1038/nsmb.1724. Epub 2009 Dec 27. Citation on PubMed or Free article on PubMed Central