Characterization and Classification of ATP-binding Cassette Transporter ABCA3 Mutants in Fatal Surfactant Deficiency

摘要: The ATP-binding cassette transporter ABCA3 is expressed predominantly at the limiting membrane of lamellar bodies in lung alveolar type II cells. Recent study has shown that mutation gene causes fatal surfactant deficiency newborns. In this study, we investigated HEK293 cells intracellular localization and N-glycosylation mutants so far identified patients. Green fluorescent protein-tagged L101P, L982P, L1553P, Q1591P, Ins1518fs/ter1519 mutant proteins remained localized endoplasmic reticulum, processing oligosaccharide was impaired, whereas wild-type N568D, G1221S, L1580P trafficked to LAMP3-positive vesicle, accompanied by from high mannose complex type. Vanadate-induced nucleotide trapping analyses showed ATP hydrolysis activity dramatically decreased mutants, a moderate decrease binding N568D but not G1221S mutant, compared with protein. addition, mutational Gly-1221 residue 11th transmembrane segment Leu-1580 cytoplasmic tail, homology modeling domain 2 demonstrate significance these residues for suggest mechanism impaired mutants. Thus, because may be classified into two categories as follows: abnormal (type I) normal and/or protein II). These distinct pathophysiologies reflect both severity effective therapy deficiency.