ADP ribosylation factor regulates spectrin binding to the Golgi complex.
Homologues of two major components of the well-characterized erythrocyte plasma-membrane-skeleton, spectrin (a not-yet-cloned isoform, betaI Sigma* spectrin) and ankyrin (AnkG119 and an approximately 195-kDa ankyrin), associate with the Golgi complex. ADP ribosylation factor (ARF) is a small G protein that controls the architecture and dynamics of the Golgi by mechanisms that remain incompletely understood. We find that activated ARF stimulates the in vitro association of betaI Sigma* spectrin with a Golgi fraction, that the Golgi-associated betaI Sigma* spectrin contains epitopes characteristic of the betaI Sigma2 spectrin pleckstrin homology (PH) domain known to bind phosphatidylinositol 4,5-bisphosphate (PtdInsP2), and that ARF recruits betaI Sigma* spectrin by inducing increased PtdInsP2 levels in the Golgi. The stimulation of spectrin binding by ARF is independent of its ability to stimulate phospholipase D or to recruit coat proteins (COP)-I and can be blocked by agents that sequester PtdInsP2. We postulate that a PH domain within betaI Sigma* Golgi spectrin binds PtdInsP2 and acts as a regulated docking site for spectrin on the Golgi. Agents that block the binding of spectrin to the Golgi, either by blocking the PH domain interaction or a constitutive Golgi binding site within spectrin's membrane association domain I, inhibit the transport of vesicular stomatitis virus G protein from endoplasmic reticulum to the medial compartment of the Golgi complex. Collectively, these results suggest that the Golgi-spectrin skeleton plays a central role in regulating the structure and function of this organelle.
Godi
A
A
Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro (Chieti), Italy 66030.
Santone
I
I
Pertile
P
P
Devarajan
P
P
Stabach
P R
PR
Morrow
J S
JS
Di Tullio
G
G
Polishchuk
R
R
Petrucci
T C
TC
Luini
A
A
De Matteis
M A
MA
D020727:ADP-Ribosylation Factors; D000818:Animals; D017487:Ankyrins / Q000378:metabolism; D001692:Biological Transport; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D008562:Membrane Glycoproteins; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D013049:Spectrin / Q000276:immunology / Q000378:metabolism*; D014759:Viral Envelope Proteins / Q000378:metabolism
D017487:Ankyrins; C028391:G protein, vesicular stomatitis virus; D008562:Membrane Glycoproteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D014759:Viral Envelope Proteins; D013049:Spectrin; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020727:ADP-Ribosylation Factors