ABCA3

ABCA3 is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN2

ATP Binding Cassette Subfamily A Member 3

Catalyzes the ATP-dependent transport of phospholipids such as phosphatidylcholine and phosphoglycerol from the cytoplasm into the lumen side of lamellar bodies, in turn participates in the lamellar bodies biogenesis and homeostasis of pulmonary surfactant. Transports preferentially phosphatidylcholine containing short acyl chains. In addition plays a role as an efflux transporter of miltefosine across macrophage membranes and free cholesterol (FC) through intralumenal vesicles by removing FC from the cell as a component of surfactant and protects cells from free cholesterol toxicity.

Cellular protein metabolic process
Drug export
Drug transmembrane transport
Lipid transport
Lung development
Organelle assembly
Phosphatidylcholine metabolic process
Phosphatidylglycerol metabolic process
Phospholipid homeostasis
Phospholipid transport
Positive regulation of cholesterol efflux
Positive regulation of phospholipid efflux
Positive regulation of phospholipid transport
Positive regulation of protein homooligomerization
Regulation of lipid biosynthetic process
Regulation of phosphatidylcholine metabolic process
Response to drug
Response to glucocorticoid
Surfactant homeostasis
Xenobiotic transport

Multivesicular body membrane; Late endosome membrane; Lysosome membrane; Cytoplasmic vesicle membrane. Localized in the limiting membrane of lamellar bodies in lung alveolar type II cells. Trafficks via the Golgi, sorting vesicles (SVs) and late endosome/multivesicular body network directly to the outer membrane of lamellar bodies in AT2 lung epithelial cells or to lysosomes and lysosomal-related organelles (LROs) in other cells where undergoes proteolytic cleveage and oligosaccharide processing from high mannose type to complex type. Oligomers formation takes place in a post-endoplasmic reticulum compartment.

A rare lung disorder due to impaired surfactant homeostasis. It is characterized by alveolar filling with floccular material that stains positive using the periodic acid-Schiff method and is derived from surfactant phospholipids and protein components. Excessive lipoproteins accumulation in the alveoli results in severe respiratory distress.

N-glycosylated. Localization at intracellular vesicles is accompanied by processing of oligosaccharide from high mannose type to complex type. N-linked glycosylation at Asn-124 and Asn-140 is required for stability and efficient anterograde trafficking and prevents from proteasomal degradation.
Proteolytically cleaved by CTSL and to a lower extent by CTSB within multivesicular bodies (MVB) and lamellar bodies (LB) leading to a mature form of 150 kDa.