Human Broad Substrate Specificity ATP-Binding Cassette Transporter ABCG2 (ABCG2) Protein

Background

ABCG2, also known as the breast cancer resistance protein (BCRP), is a well-characterized ATP-binding cassette transporter involved in drug efflux and xenobiotic clearance. It is highly expressed in barrier tissues such as the intestine, liver, kidneys, and blood-brain barrier, where it protects cells by exporting a wide range of substrates, including drugs, toxins, and endogenous metabolites. ABCG2 plays a pivotal role in pharmacokinetics, influencing drug absorption, distribution, and elimination. It is also critical in stem cell biology, where it acts as a marker for side population cells due to its role in drug resistance and dye efflux. Overexpression of ABCG2 is a major contributor to multidrug resistance in cancer, as it actively pumps chemotherapeutic agents out of tumor cells, reducing their efficacy. Structurally, ABCG2 is a half-transporter that forms functional homodimers to mediate ATP-driven substrate transport. Dysregulation of ABCG2 has been linked to diseases such as gout and certain cancers, making it a target of interest in oncology and pharmacology.