Possible role of BARS-50, a substrate of brefeldin A-dependent mono-ADP-ribosylation, in intracellular transport.
Brefeldin A (BFA), a fungal metabolite that inhibits membrane transport, potently stimulates an endogenous ADP-ribosylation reaction that selectively modifies two cytosolic proteins of 38 and 50 kDa on an amino acid residue different from those used by all known mADPRTs. The 38-kDa substrate was identified as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH), whereas the 50-kDa substrate (BARS-50) was characterized as a novel guanine nucleotide binding protein. Thus, BARS-50 is able to bind GTP and its ADP-ribosylation is inhibited by the beta gamma subunit of GTP-binding (G) proteins. Moreover, BARS-50 was demonstrated to be a group of closely related proteins that appear to be different from all the known G proteins. A partially purified BARS-50 was obtained from rat brain cytosol, which was then used for microsequencing and in functional studies. A similar procedure led to the purification of native (non-ADP-ribosylated) BARS-50. The possible role of the BFA-dependent ADP-ribosylation and of BARS-50 in the maintenance of Golgi structure and function was addressed by examining which of the effects of BFA may be modified by inhibiting this reaction. We find that the BFA-dependent transformation of the Golgi stacks into a tubular reticular network is prevented when the BFA-dependent ADP-ribosylation activity was blocked by specific inhibitors thus indicating that BFA-dependent ADP-ribosylation of cytosolic proteins participate in the dynamic regulation of intracellular transport.
Silletta
M G
MG
Department of Cell Biology and Oncology, Istituto di Ricerche Farmacologiche Mario Negri, Santa Maria Imbaro (Chieti), Italy.
Di Girolamo
M
M
Fiucci
G
G
Weigert
R
R
Mironov
A
A
De Matteis
M A
MA
Luini
A
A
Corda
D
D
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D020126:Brefeldin A; D002460:Cell Line; D003517:Cyclopentanes / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D013379:Substrate Specificity
D003517:Cyclopentanes; D020126:Brefeldin A; D000246:Adenosine Diphosphate Ribose; D019204:GTP-Binding Proteins