TMEM38B

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
Identifiers
Aliases	TMEM38B, C9orf87, D4Ertd89e, OI14, TRIC-B, TRICB, bA219P18.1, transmembrane protein 38B
External IDs	OMIM: 611236; MGI: 1098718; HomoloGene: 10010; GeneCards: TMEM38B; OMA:TMEM38B - orthologs
Gene location (Mouse) Chr. Chromosome 4 (mouse)[1] Band 4 B2|4 28.76 cM Start 53,826,045 bp[1] End 53,862,019 bp[1]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in sperm biceps brachii right ventricle tibialis anterior muscle gastrocnemius muscle vastus lateralis muscle deltoid muscle islet of Langerhans corpus epididymis Achilles tendon Top expressed in gastrula parotid gland temporal muscle triceps brachii muscle sternocleidomastoid muscle thoracic diaphragm submandibular gland granulocyte digastric muscle knee joint More reference expression data BioGPS n/a
Gene ontology Molecular function potassium channel activity cation channel activity calcium-activated potassium channel activity Cellular component membrane integral component of membrane nuclear membrane endoplasmic reticulum membrane endoplasmic reticulum sarcoplasmic reticulum membrane nucleus Biological process potassium ion transport ion transport potassium ion transmembrane transport transport ossification endoplasmic reticulum organization phospholipid biosynthetic process regulation of cardiac muscle contraction by regulation of the release of sequestered calcium ion release of sequestered calcium ion into cytosol by sarcoplasmic reticulum bone mineralization lung alveolus development release of sequestered calcium ion into cytosol bone development lung epithelial cell differentiation secretion by lung epithelial cell involved in lung growth extracellular matrix constituent secretion cellular response to caffeine release of sequestered calcium ion into cytosol by endoplasmic reticulum cation transmembrane transport ion transmembrane transport Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 55151 52076 Ensembl n/a ENSMUSG00000028420 UniProt Q9NVV0 Q9DAV9 RefSeq (mRNA) NM_018112 NM_028053 RefSeq (protein) NP_060582 NP_082329 Location (UCSC) n/a Chr 4: 53.83 – 53.86 Mb PubMed search [2] [3]
Wikidata
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Function

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

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

• TMEM38A
• Trimeric intracellular cation-selective channel