ArfGAP3 is a component of the photoreceptor synaptic ribbon complex and forms an NAD(H)-regulated, redox-sensitive complex with RIBEYE that is important for endocytosis.
Ribbon synapses are tonically active synapses in the retina and inner ear with intense vesicle traffic. How this traffic is organized and regulated is still unknown. Synaptic ribbons, large presynaptic structures associated with numerous synaptic vesicles, appear to be essential for this process. The base of the synaptic ribbon is anchored at the active zone and is a hotspot of exocytosis. The synaptic ribbon complex is also important for vesicle replenishment. RIBEYE is a unique and major component of synaptic ribbons. It consists of a unique A-domain and an NAD(H)-binding, C-terminal B-domain. In the present study, we show that the Arf-GTPase activating protein-3 (ArfGAP3), a well characterized regulator of vesicle formation at the Golgi apparatus, is also a component of the synaptic ribbon complex in photoreceptor synapses of the mouse retina and interacts with RIBEYE as shown by multiple, independent approaches. ArfGAP3 binds to RIBEYE(B)-domain in an NAD(H)-dependent manner. The interaction is redox sensitive because NADH is more efficient than the oxidized NAD(+) in promoting ArfGAP3-RIBEYE interaction. RIBEYE competes with the GTP-binding protein Arf1 for binding to ArfGAP3. Thus, binding of RIBEYE(B) to ArfGAP3 could prevent inactivation of Arf1 by ArfGAP3 and provides the synaptic ribbon with the possibility to control Arf1 function. The interaction is relevant for endocytic vesicle trafficking because overexpression of ArfGAP3 in photoreceptors strongly inhibited endocytotic uptake of FM1-43.
Saarland University, Medical School, Department of Neuroanatomy, 66421 Homburg/Saar, Germany.
Mayur
M
Dembla
Silke
S
Wahl
Rashmi
R
Katiyar
Frank
F
Schmitz
D020823:ADP-Ribosylation Factor 1 / Q000378:metabolism; D000429:Alcohol Oxidoreductases; D000818:Animals; D019556:COS Cells; D002417:Cattle; D002522:Chlorocebus aethiops; D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009243:NAD / Q000378:metabolism*; D010084:Oxidation-Reduction; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010786:Photoreceptor Cells / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding; D013569:Synapses / Q000378:metabolism* / Q000502:physiology
C503241:Arfgap3 protein, mouse; D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins; D020690:GTPase-Activating Proteins; D010750:Phosphoproteins; D009243:NAD; D000429:Alcohol Oxidoreductases; C111341:Ctbp2 protein, mouse; D020823:ADP-Ribosylation Factor 1
ArfGAP3; RIBEYE; endocytosis; photoreceptor synapse; ribbon synapse; synaptic ribbon