ABCA3 is a lamellar body membrane protein in human lung alveolar type II cells¹

TLDR

The ABCA3 gene, an ABCA subclass ATP‑binding cassette transporter, is expressed exclusively in lung and, like other ABCA transporters, is implicated in transmembrane lipid transport. The authors cloned the human ABCA3 gene, performed molecular characterization, and mapped its distribution in lung tissue. Immunoblotting revealed a 150‑kDa ABCA3 protein in the crude membrane fraction, and immunohistochemistry showed its expression confined to surfactant‑protein‑A–positive type II cells, with localization mainly at lamellar body limiting membranes, supporting a role for ABCA3 in pulmonary surfactant formation.

Abstract

The ABCA3 gene, of the ABCA subclass of ATP‐binding cassette (ABC) transporters, is expressed exclusively in lung. We report here the cloning, molecular characterization, and distribution of human ABCA3 in the lung. Immunoblot analysis using the specific antibody reveals a 150‐kDa protein in the crude membrane fraction of human lung. Immunohistochemical analyses of alveoli show that ABCA3 is expressed only in the type II cells expressing surfactant protein A. At the ultrastructural level, ABCA3 immunoreactivity was detected mostly at the limiting membrane of the lamellar bodies. Since members of the ABCA transporter family are known to be involved in transmembrane transport of endogenous lipids, our findings suggest that ABCA3 plays an important role in the formation of pulmonary surfactant in type II cells.