A BAR domain in the N terminus of the Arf GAP ASAP1 affects membrane structure and trafficking of epidermal growth factor receptor.
BACKGROUND
Arf GAPs are multidomain proteins that function in membrane traffic by inactivating the GTP binding protein Arf1. Numerous Arf GAPs contain a BAR domain, a protein structural element that contributes to membrane traffic by either inducing or sensing membrane curvature. We have examined the role of a putative BAR domain in the function of the Arf GAP ASAP1.


RESULTS
ASAP1's N terminus, containing the putative BAR domain together with a PH domain, dimerized to form an extended structure that bound to large unilamellar vesicles containing acidic phospholipids, properties that define a BAR domain. A recombinant protein containing the BAR domain of ASAP1, together with the PH and Arf GAP domains, efficiently bent the surface of large unilamellar vesicles, resulting in the formation of tubular structures. This activity was regulated by Arf1*GTP binding to the Arf GAP domain. In vivo, the tubular structures induced by ASAP1 mutants contained epidermal growth factor receptor (EGFR) and Rab11, and ASAP1 colocalized in tubular structures with EGFR during recycling of receptor. Expression of ASAP1 accelerated EGFR trafficking and slowed cell spreading. An ASAP1 mutant lacking the BAR domain had no effect.


CONCLUSIONS
The N-terminal BAR domain of ASAP1 mediates membrane bending and is necessary for ASAP1 function. The Arf dependence of the bending activity is consistent with ASAP1 functioning as an Arf effector.
Nie
Zhongzhen
Z
Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA.
Hirsch
Dianne S
DS
Luo
Ruibai
R
Jian
Xiaoying
X
Stauffer
Stacey
S
Cremesti
Aida
A
Andrade
Josefa
J
Lebowitz
Jacob
J
Marino
Michael
M
Ahvazi
Bijan
B
Hinshaw
Jenny E
JE
Randazzo
Paul A
PA
D020727:ADP-Ribosylation Factors / Q000502:physiology; D048868:Adaptor Proteins, Signal Transducing / Q000032:analysis / Q000737:chemistry* / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure*; D066246:ErbB Receptors / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000032:analysis / Q000737:chemistry* / Q000502:physiology*; D051379:Mice; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D016415:Sequence Alignment
D048868:Adaptor Proteins, Signal Transducing; C485546:Asap1 protein, mouse; D020690:GTPase-Activating Proteins; D066246:ErbB Receptors; D020727:ADP-Ribosylation Factors