Translocation of Arf1 to the secretory granules in rat parotid acinar cells.
We investigated the interaction of ADP-ribosylation factor (Arf) with the secretory granules in rat parotid acinar cells. The 20. 5-kDa small-molecular-mass GTP-binding protein in the cytosolic fraction of rat parotid acinar cells was identified as ADP-ribosylation factor1 by using a pan-Arf monoclonal antibody and isotype-specific polyclonal antibodies for Arf proteins 1, 3, 5, and 6. Incubation of the cytosolic fraction with isolated secretory granule membranes in the presence of GTPgammaS resulted in the translocation of Arf1 from the cytosolic fraction to the secretory granule membranes. The translocation was not observed in the presence of GDPbetaS in place of GTPgammaS, indicating that the process is GTP-dependent. The immunoelectron microscopy experiment confirmed Arf1 is translocated to the secretory granules. A prior treatment of the granule membranes with trypsin inhibited the translocation of Arf1 at 2 mM Mg2+, but had no effect in the absence of Mg2+ (condition of spontaneous conversion of Arf-GDP to Arf-GTP). Thus, the trypsin-sensitive nucleotide exchange activity for Arf1 is probably associated with the secretory granule membranes. These results demonstrate Arf1 translocates to the secretory granules in rat parotid acinar cells.
Dohke
Y
Y
Department of Physiology, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakae-cho Nishi, Chiba, Matsudo, 271-8587, Japan.
Hara-Yokoyama
M
M
Fujita-Yoshigaki
J
J
Kahn
R A
RA
Kanaho
Y
Y
Hashimoto
S
S
Sugiya
H
H
Furuyama
S
S
D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D002458:Cell Fractionation; D020756:Coatomer Protein; D003594:Cytoplasmic Granules / Q000737:chemistry / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000378:metabolism; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D010306:Parotid Gland / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D002352:Carrier Proteins; D020756:Coatomer Protein; D006150:Guanine Nucleotides; D008565:Membrane Proteins; D019204:GTP-Binding Proteins; D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors