SLC51B Membrane Protein Introduction

Introduction of SLC51B

SLC51B encoded by SLC51B gene, also known as OSTβ, is a predicted 128-amino acid, single transmembrane (TM) domain protein. It combines with SLC51A (OSTα) and forms a functional heterodimeric transporter, designated as OSTα-OSTβ. The organic solute transporter OSTα-OSTβ is expressed at the basolateral membrane of epithelium in intestine, kidney, liver, testis, and adrenal gland and involved in the mediation of intestinal absorption of bile acids and the enterohepatic circulation.

Basic Information of SLC51B
Protein Name Organic solute transporter subunit beta
Gene Name Q86UW2
Aliases OSTB, OSTbeta
Organism Homo sapiens (Human)
UniProt ID Q86UW2
Transmembrane Times 1
Length (aa) 128

Function of SLC51B Membrane Protein

SLC51B (OSTβ) is an essential component of the OSTα-OSTβ heterodimer complex that functions as the intestinal basolateral transporter mediating bile acid export from enterocytes into portal blood. And it is essential for intestinal bile acid absorption, and thus for dietary lipid absorption. Besides, OSTα-OSTβ heterodimer complex also participates in the transport of estrone sulfate, taurocholate, digoxin, and prostaglandin E2 across cell membranes. Studies have revealed that the transporter is selectively located to steroidogenic cells of the brain and adrenal gland and transports conjugated steroids, including some neurosteroids, which suggests OSTα-OSTβ may contribute to neurosteroid action. Furthermore, Ostα-Ostβ is also involved in many signaling pathways and biological processes such as triglyceride, glucose and energy homeostasis. In addition, OSTα/β is associated with bile duct disease and biliary tract disease. The elevated expression of OSTα/β is observed in the liver of patients with nonalcoholic steatohepatitis and primary biliary cholangitis.

Selected transporters for endogenous compounds and xenobiotics, expressed on the sinusoidal and canalicular membranes of human hepatocytes. Fig.1 Selected transporters for endogenous compounds and xenobiotics, expressed on the sinusoidal and canalicular membranes of human hepatocytes. (Niemi, 2011)

Application of SLC51B Membrane Protein in Literature

  1. Xu S., et al. A novel di-leucine motif at the n-terminus of human organic solute transporter beta is essential for protein association and membrane localization. Plos One. 2016, 11(6): e0158269. PubMed ID: 27351185

    In this study, results indicate that the dileucine motif in the extracellular N-terminal region of OSTβ subunit is very important for the association with OSTα subunit and for its polarized plasma membrane localization.

  2. Fang F., et al. Neurosteroid transport by the organic solute transporter OSTα-OSTβ. Journal of Neurochemistry. 2010, 115(1): 220-233. PubMed ID: 20649839

    The article demonstrates that OSTα-OSTβ is selectively located to steroidogenic cells of the brain and adrenal gland and that it regulates DHEA/DHEAS homeostasis.

  3. Sultan M., et al. Organic solute transporter-beta (slc51b) deficiency in two brothers with congenital diarrhea and features of cholestasis. Hepatology. 2017. PubMed ID: 28898457

    This study reports that patients with SLC51B deficiency clinically exhibit congenital chronic diarrhea with the features of cholestatic liver disease.

  4. Schaffner C.A., et al. The organic solute transporters alpha and beta are induced by hypoxia in human hepatocytes. Liver International. 2015, 35(4): 1152-61. PubMed ID: 24703425

    Hypoxia in hepatocytes is induced by liver injury caused by ischemia-reperfusion, cancer, inflammation or cholestasis. The aim of this study is to investigate the effect of hypoxia on the expression of OSTα-OSTβ and the data suggest OSTα-OSTβ expression is induced by hypoxia.

  5. Ballatori N., et al. Ostalpha-Ostbeta is required for bile acid and conjugated steroid disposition in the intestine, kidney, and liver. Am J Physiol Gastrointest Liver Physiol. 2008, 295(1): G179-G186. PubMed ID: 18497332

    The data of this research support the hypothesis that OSTα-OSTβ is an essential basolateral transporter of bile acids and conjugated steroids in the intestine, liver, and kidney.

SLC51B Preparation Options

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  1. Niemi M, et al. (2011). Organic anion transporting polypeptide 1B1: a genetically polymorphic transporter of major importance for hepatic drug uptake. Pharmacological Reviews. 63(1), 157-181.

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