ATP-binding cassette subfamily G member 5 (ABCG5)

**ATP-binding cassette subfamily G member 5 (ABCG5)** is a membrane-bound ATP-dependent transporter essential for the maintenance of cholesterol and plant sterol homeostasis in humans[1][3][5][6]. It functions as a "half-transporter," requiring dimerization with ABCG8 to form the functional ABCG5/ABCG8 complex. This heterodimer, expressed primarily in the liver, intestine, and colon, actively promotes the **efflux of dietary cholesterol and plant sterols** from enterocytes back into the intestinal lumen and from hepatocytes into bile, limiting absorption and facilitating excretion of non-cholesterol sterols[4][7][8][9]. **Mutations in ABCG5 cause sitosterolemia**, a rare inherited disease characterized by excessive accumulation of plant sterols, tendon xanthomas, and increased risk of premature atherosclerosis and cardiovascular disease. ABCG5 is classified as a transporter in the **White subfamily of ATP-binding cassette transporters**[3]. There are currently no drugs directly targeting ABCG5, but its activity is counter-regulated by NPC1L1, which is inhibited by ezetimibe to reduce intestinal sterol absorption[4]. Plasma phytosterol levels and ABCG5 sequencing are used as biomarkers for patient diagnosis and risk stratification in lipid disorders[1][7]. Safety concerns primarily arise from genetic deficiency, leading to sterol accumulation and associated disease.

Other names

Sterolin-1STSLSTSL2sterolin 1sterolinATP-binding cassette, sub-family G (WHITE), member 5

Inhibition of NPC1L1 (not direct ABCG5 modulation); no currently approved drugs specifically target ABCG5 function directly[4]