ABCA1

ATP binding cassette subfamily A member 1

3 disorders 2 untyped 1 modifier 9q31.1 gene with protein product

HGNC:29 Monarch NCBI Gene 19 ENSG00000165029 UniProt O95477 OMIM 600046

Previous symbols: ABC1, HDLDT1. Aliases: TGD.

Normal function · from ai-gene-review (O95477, commit 79fe13b38970) · AI-generated, not KB evidence

ABCA1 encodes a large ATP-binding cassette subfamily A multipass membrane transporter that uses ATP binding and hydrolysis to move phospholipids across membrane leaflets and to support cholesterol/phospholipid efflux to apolipoproteins. It localizes mainly to the plasma membrane and cell surface with endosomal/vesicular trafficking, binds apoA-I and other exchangeable apolipoproteins including apoE, and promotes nascent HDL particle formation, reverse cholesterol transport, and cellular lipid homeostasis. Loss of ABCA1 function causes Tangier disease and familial HDL deficiency, and in brain-relevant lipid biology ABCA1 is important for APOE lipidation and cholesterol handling.

ABCA1 uses ATP binding and hydrolysis to translocate phospholipids across membrane leaflets, with direct support for phosphatidylcholine, phosphatidylserine, and sphingomyelin movement and for extracellular phospholipid extraction at the plasma membrane.

molecular function: ATPase-coupled intramembrane lipid transporter activity · directly involved in: phospholipid translocation; phospholipid efflux; sphingolipid translocation · locations: plasma membrane; cell surface; endosome

ABCA1 binds apoA-I and other exchangeable apolipoproteins, including APOE, to drive cellular cholesterol and phospholipid efflux, nascent HDL particle assembly, and reverse cholesterol transport. This lipidation activity is the ABCA1 function most directly connected to APOE biology.

molecular function: apolipoprotein A-I receptor activity · directly involved in: cholesterol efflux; high-density lipoprotein particle assembly; reverse cholesterol transport; positive regulation of high-density lipoprotein particle assembly; cholesterol homeostasis · locations: plasma membrane; cell surface; endocytic vesicle

ABCA1 contributes to cholesterol movement out of cells and away from intracellular pools, limiting cholesterol storage and promoting HDL-associated lipid removal. This cholesterol-efflux role is supported by Tangier/familial HDL-deficiency genetics and cellular efflux assays, although the direct transported lipid substrate is best established for phospholipids.

molecular function: cholesterol transfer activity · directly involved in: cholesterol transport; cholesterol efflux; intracellular cholesterol transport; negative regulation of cholesterol storage; cholesterol metabolic process · locations: plasma membrane; endosome

In the knowledge base · computed from kb/ at build time

Disorders

Relationship is the entry's genetic[].relationship_type. untyped means the entry has a genetic record for the gene but does not type it; its free-text association is shown instead.

Disorder	Relationship	Where the gene appears
MEND Syndrome	modifier
Smith-Lemli-Opitz syndrome	untyped Modifier
Tangier_Disease	untyped Causative	mechanism: ABCA1 Dysfunction

Identity from HGNC (snapshot 2026-10-01). Page layers are described in the gene pages documentation.