TABLE 1

An overview of the expression and functions of ABCG2

In addition to these locations, ABCG2 has been found in the adrenal gland, cervix and uterus, bladder, and lungs.

Location of ABCG2Action/Function at SiteReference
Small intestine enterocytesEfflux of compounds into lumen of GI tract; reduced absorption of drugs into bloodstream; protection of body from absorption of toxins and xenobiotics; extrarenal clearance of uric acidMaliepaard et al. (2001); Taipalensuu et al. (2001)
Liver canalicular membraneTransport of compounds from bloodstream into hepatocytes and liver canaliculi; increased excretion of compounds via bileMaliepaard et al. (2001)
Proximal tubule cells in kidneyTransport from blood into proximal renal tubule; increased excretion of compounds via urine; role in excretion of uric acidMaliepaard et al. (2001)
Blood-brain barrierEfflux of compounds from endothelial cells into microvessels; protection of brain from toxic compounds; role in tolerance to CNS drugs, e.g., opioids; potential role in CNS diseases, e.g., Alzheimer’s disease and Parkinson’s diseaseCooray et al. (2002)
Placental syncytiotrophoblastsTransports compounds across placenta from fetus into maternal circulation; protection of fetus from toxins and xenobioticsMaliepaard et al. (2001); Memon et al. (2014)
Mammary glandTransports compounds into breast milk; modulation of vitamin levels; potential harmful value to infant if mother is receiving drug treatment while breast feedingVlaming et al. (2009)
ErythrocytesEfflux of porphyrins from cell; upregulated in erythroid maturation; modulation of protoporphyrin IX; determinant in protoporphyriaZhou et al. (2005)
Hematopoietic stem cellsEfflux of porphyrins from cell; protection from hypoxia and accumulation of haem; role in stem cell phenotype; role in hematologic cancer prognosisScharenberg et al. (2002); Krishnamurthy et al. (2004)
Hair follicleProtection of the root sheathHaslam et al. (2015)
Basal epithelial cells of prostateEfflux of differentiation-inducing molecules; role in self-renewal and development of prostate stem cells; role in regulation of testosteroneHuss et al. (2005); Pascal et al. (2007)
Blood-testis barrierEfflux of compounds from Sertoli cells into interstitium; protection of developing spermatozoa from xenobiotics and toxinsRobillard et al. (2012)
Harderian glandTransport into tubulo-alveolar lumen of gland secretions of lipids and porphyrinsVlaming et al. (2009)
Inner blood-retinal barrierEfflux of toxins out of retina; protection from phototoxicityVlaming et al. (2009); Zhang et al. (2017)
  • CNS, central nervous system; GI, gastrointestinal.