Summary
Trimeric intracellular cation-selective channel B (TRIC-B) is a monovalent cation channel in the ER membrane encoded by the transmembrane protein 38B (TMEM38B) gene.[4][5] It is one of two known TRIC proteins, the other being TRIC-A.
| TMEM38B | |||||||||||||||||||||||||||||||||||||||||||||||||||
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| Aliases | TMEM38B, C9orf87, D4Ertd89e, OI14, TRIC-B, TRICB, bA219P18.1, transmembrane protein 38B | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 611236 MGI: 1098718 HomoloGene: 10010 GeneCards: TMEM38B | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Function edit
TRIC-B is permeable to both Na+ and K+ but not divalent cations like Ca2+.[4] The channel exhibits marked voltage-dependence, becoming more open when the cytosol is more positively charged than the ER lumen. There at least four major sub-conductance states (with 80%, 60%, 46% and 30% of the conductance of the fully-opened channel).[4] TMEM38B-knockout mice exhibit reduced IP3-receptor-mediated Ca2+ release.[4] As such, K+ flux into the ER through TRIC-B is thought to support IP3-induced efflux of Ca2+ ions through IP3-gated Ca2+ channels in the ER membrane.
Clinical significance edit
Null mutations in TMEM38B reduce the levels of functional TRIC-B in heterozygotes and abolish expression of functional TRIC-B in homozygotes. Such mutations are an uncommon but relatively severe cause of autosomal recessive osteogenesis imperfecta or "brittle bone disease".[5]
See also edit
References edit
- ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000028420 – Ensembl, May 2017
- ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ a b c d Venturi, Elisa; Sitsapesan, Rebecca; Yamazaki, Daiju; Takeshima, Hiroshi (15 December 2012). "TRIC channels supporting efficient Ca2+ release from intracellular stores". European Journal of Physiology. 465 (2): 187–195. doi:10.1007/s00424-012-1197-5. PMID 23242030. S2CID 14397400.
- ^ a b Cabral, Wayne A.; Ishikawa, Masaki; Garten, Matthias; Makareeva, Elena N.; Sargent, Brandi M.; Weis, MaryAnn; Barnes, Aileen M.; Webb, Emma A.; Shaw, Nicholas J.; Ala-Kokko, Leena; Lacbawan, Felicitas L.; Högler, Wolfgang; Leikin, Sergey; Blank, Paul S.; Zimmerberg, Joshua; Eyre, David R.; Yamada, Yoshihiko; Marini, Joan C. (21 July 2016). "Absence of the ER Cation Channel TMEM38B/TRIC-B Disrupts Intracellular Calcium Homeostasis and Dysregulates Collagen Synthesis in Recessive Osteogenesis Imperfecta". PLOS Genetics. 12 (7): e1006156. doi:10.1371/journal.pgen.1006156. PMC 4956114. PMID 27441836.