Protein kinase A site-specific phosphorylation regulates ATP-binding cassette A1 (ABCA1)-mediated phospholipid efflux.
ATP-binding cassette A1 (ABCA1) is a key mediator of cholesterol and phospholipid efflux to apolipoprotein particles. We show that ABCA1 is a constitutively phosphorylated protein in both RAW macrophages and in a human embryonic kidney cell line expressing ABCA1. Furthermore, we demonstrate that phosphorylation of ABCA1 is mediated by protein kinase A (PKA) or a PKA-like kinase in vivo. Through site-directed mutagenesis studies of consensus PKA phosphorylation sites and in vitro PKA kinase assays, we show that Ser-1042 and Ser-2054, located in the nucleotide binding domains of ABCA1, are major phosphorylation sites for PKA. ApoA-I-dependent phospholipid efflux was decreased significantly by mutation of Ser-2054 alone and Ser-1042/Ser-2054 but was not significantly impaired with Ser-1042 alone. The mechanism by which ABCA1 phosphorylation affected ApoA-I-dependent phospholipid efflux did not involve either alterations in ApoA-I binding or changes in ABCA1 protein stability. These studies demonstrate a novel serine (Ser-2054) on the ABCA1 protein crucial for PKA phosphorylation and for regulation of ABCA1 transporter activity.
See
Raymond H
RH
Center for Molecular Medicine and Therapeutics, Department of Medical Genetics and Children's and Women's Hospital, University of British Columbia, Vancouver, Canada.
Caday-Malcolm
Rosalinda A
RA
Singaraja
Roshni R
RR
Zhou
Steven
S
Silverston
Anthony
A
Huber
Mary T
MT
Moran
Josh
J
James
Erick R
ER
Janoo
Rozmin
R
Savill
Jane M
JM
Rigot
Veronique
V
Zhang
Lin-Hua
LH
Wang
Minghan
M
Chimini
Giovanna
G
Wellington
Cheryl L
CL
Tafuri
Sherrie R
SR
Hayden
Michael R
MR
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D016632:Apolipoprotein A-I / Q000378:metabolism; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism*; D010766:Phosphorylation; D012694:Serine; D013329:Structure-Activity Relationship
C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D016632:Apolipoprotein A-I; D010743:Phospholipids; D012694:Serine; D017868:Cyclic AMP-Dependent Protein Kinases