The KDEL receptor regulates a GTPase-activating protein for ADP-ribosylation factor 1 by interacting with its non-catalytic domain.
ADP-ribosylation factor 1 (ARF1) is a key regulator of transport in the secretory system. Like all small GTPases, deactivation of ARF1 requires a GTPase-activating protein (GAP) that promotes hydrolysis of GTP to GDP on ARF1. Structure-function analysis of a GAP for ARF1 revealed that its activity in vivo requires not only a domain that catalyzes hydrolysis of GTP on ARF1 but also a non-catalytic domain. In this study, we show that the non-catalytic domain of GAP is required for its recruitment from cytosol to membranes and that this domain mediates the interaction of GAP with the transmembrane KDEL receptor. Blocking its interaction with the KDEL receptor leaves the GAP cytosolic and prevents the deactivation in vivo of Golgi-localized ARF1. Thus, these findings suggest that the KDEL receptor plays a critical role in the function of GAP by regulating its recruitment from cytosol to membranes, where it can then act on its membrane-restricted target, the GTP-bound form of ARF1.
Aoe
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T
Division of Rheumatology, Allergy, and Immunology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Huber
I
I
Vasudevan
C
C
Watkins
S C
SC
Romero
G
G
Cassel
D
D
Hsu
V W
VW
D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors; D000818:Animals; D019556:COS Cells; D020134:Catalytic Domain; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D009154:Mutation; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D018000:Receptors, Peptide / Q000235:genetics / Q000378:metabolism*
D020690:GTPase-Activating Proteins; C064459:KDEL receptor; D011506:Proteins; D018000:Receptors, Peptide; D019204:GTP-Binding Proteins; D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors