Biochemical characterization of P4-ATPase mutations identified in patients with progressive familial intrahepatic cholestasis.
Mutations in the P4-ATPase ATP8B1 cause the inherited liver disease progressive familial intrahepatic cholestasis. Several of these mutations are located in conserved regions of the transmembrane domain associated with substrate binding and transport. Assays for P4-ATPase-mediated transport in living yeast cells were developed and used to characterize the specificity and kinetic parameters of this transport. Progressive familial intrahepatic cholestasis mutations were introduced into the yeast plasma membrane P4-ATPase Dnf2p, and the effect of these mutations on its catalysis of phospholipid transport were determined. The results of these measurements have implications for the basis of the disease and for the mechanism of phospholipid transit through the enzyme during the reaction cycle.
Department of Biology, Amherst College, Amherst, Massachusetts 01002, USA.
Alex
A
Stone
Christopher
C
Chau
Christian
C
Eaton
Emily
E
Foran
Mridu
M
Kapur
Edward
E
Prevatt
Nathan
N
Belkin
David
D
Kerr
Torvald
T
Kohlin
Patrick
P
Williamson
D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics*; D000595:Amino Acid Sequence; D002780:Cholestasis, Intrahepatic / Q000235:genetics*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010743:Phospholipids / Q000737:chemistry; D012044:Regression Analysis; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D018528:ATP-Binding Cassette Transporters; C427246:CDC50 protein, S cerevisiae; D010743:Phospholipids; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases; C480602:Dnf2 protein, S cerevisiae; C111067:ATP8B1 protein, human