ATP-binding cassette sub-family A member 3

Multifunctional polypeptide with two homologous halves, each containing a hydrophobic membrane-anchoring domain and an ATP binding cassette (ABC) domain.

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 (PubMed:16959783, PubMed:17574245, PubMed:27177387, PubMed:28887056, PubMed:31473345). Transports preferentially phosphatidylcholine containing short acyl chains (PubMed:27177387). 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 (PubMed:25817392, PubMed:26903515, PubMed:27177387).

Pulmonary surfactant metabolism dysfunction 3

SMDP3

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.

None

The disease is caused by variants affecting the gene represented in this entry.

N-glycosylated (PubMed:16959783, PubMed:24142515, PubMed:27177387). Localization at intracellular vesicles is accompanied by processing of oligosaccharide from high mannose type to complex type (PubMed:16959783, PubMed:27177387). N-linked glycosylation at Asn-124 and Asn-140 is required for stability and efficient anterograde trafficking and prevents from proteasomal degradation (PubMed:24142515).

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.

Belongs to the ABC transporter superfamily. ABCA family.

Expressed in brain, pancreas, skeletal muscle and heart (PubMed:8706931). Highly expressed in the lung in an AT2-cell-specific manner (PubMed:11718719, PubMed:8706931). Weakly expressed in placenta, kidney and liver (PubMed:8706931). Also expressed in medullary thyroid carcinoma cells (MTC) and in C-cell carcinoma (PubMed:8706931).

• Endosome
• Multivesicular body membrane
• Multi-pass membrane protein
• Cytoplasmic vesicle membrane
• Late endosome membrane
• Lysosome membrane
• Localized in the limiting membrane of lamellar bodies in lung alveolar type II cells (PubMed:11718719, PubMed:16959783, PubMed:22673903, PubMed:24142515, PubMed:27177387). 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 cleavage and oligosaccharide processing from high mannose type to complex type (PubMed:16959783, PubMed:20863830, PubMed:24142515, PubMed:27177387). Oligomers formation takes place in a post-endoplasmic reticulum compartment (PubMed:27352740).

ABC3, ABCA3, Phospholipid-transporting ATPase ABCA3, ABC-C transporter, ATP-binding cassette sub-family A member 3, ATP-binding cassette transporter 3, Xenobiotic-transporting ATPase ABCA3, ATP-binding cassette 3

• entrezGene:21
• omim:601615
• swissprot:Q99758

Proteins

Immunology & Infectious Disease

24002Da