Human ABCA3, a product of a responsible gene for abca3 for fatal surfactant deficiency in newborns, exhibits unique ATP hydrolysis activity and generates intracellular multilamellar vesicles.
ABCA3 is highly expressed at the membrane of lamellar bodies in alveolar type II cells, in which pulmonary surfactant is stored. ABCA3 gene mutations cause fatal surfactant deficiency in newborns. We established HEK293 cells stably expressing human ABCA3 and analyzed the function. Exogenously expressed ABCA3 is glycosylated and localized at the intracellular vesicle membrane. ABCA3 is efficiently photoaffinity labeled by 8-azido-[alpha(32)P]ATP, but not by 8-azido-[gamma(32)P]ATP, when the membrane fraction is incubated in the presence of orthovanadate. Photoaffinity labeling of ABCA3 shows unique metal ion-dependence and is largely reduced by membrane pretreatment with 5% methyl-beta-cyclodextrin, which depletes cholesterol. Electron micrographs show that HEK293/hABCA3 cells contain multivesicular, lamellar body-like structures, which do not exist in HEK293 host cells. Some fuzzy components such as lipids accumulate in the vesicles. These results suggest that ABCA3 shows ATPase activity, which is induced by lipids, and may be involved in the biogenesis of lamellar body-like structures.
Nagata
Koh
K
Laboratory of Cellular Biochemistry, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
Yamamoto
Akitsugu
A
Ban
Nobuhiro
N
Tanaka
Arowu R
AR
Matsuo
Michinori
M
Kioka
Noriyuki
N
Inagaki
Nobuya
N
Ueda
Kazumitsu
K
D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism*; D002458:Cell Fractionation; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D022162:Cytoplasmic Vesicles / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008670:Metals / Q000737:chemistry; D009154:Mutation; D009711:Nucleotides / Q000378:metabolism; D019920:Photoaffinity Labels / Q000378:metabolism; D011663:Pulmonary Surfactants; D014638:Vanadates / Q000378:metabolism; D047392:beta-Cyclodextrins / Q000378:metabolism
C441524:ABCA3 protein, human; D018528:ATP-Binding Cassette Transporters; D008670:Metals; D009711:Nucleotides; D019920:Photoaffinity Labels; D011663:Pulmonary Surfactants; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D014638:Vanadates; D000255:Adenosine Triphosphate