Involvement of rabphilin-3A in Ca2+-dependent exocytosis from PC12 cells.
Rabphilin-3A, a putative target molecule of Rab3A small GTP-binding protein implicated in Ca2+-dependent exocytosis, consists of two functionally different domains: the N-terminal Rab3A-binding domain and the C-terminal two C2-like domains (C2A and C2B domains) interacting with Ca2+ and phospholipid. Here, we used the growth hormone (GH) co-expression assay system of PC12 cells in which expressed GH is released in response to high K+. Reduction of endogenous rabphilin-3A inhibited the Ca2+-dependent, high K+-induced GH release. Various rabphilin-3A mutants expressing an N-terminal, C-terminal, or C2B fragment, but not the rabphilin-3A mutant expressing a C2A fragment, inhibited the high K+-induced GH release. These results indicate that rabphilin-3A is involved at least in Ca2+-dependent exocytosis from PC12 cells and that the C2A and C2B domains have different functions.
Komuro
R
R
Department of Molecular Biology and Biochemistry, Osaka University Medical School, Suita, Japan.
Sasaki
T
T
Orita
S
S
Maeda
M
M
Takai
Y
Y
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005089:Exocytosis; D019204:GTP-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D013006:Growth Hormone / Q000096:biosynthesis; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016254:Mutagenesis, Insertional; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000378:metabolism*; D016716:PC12 Cells; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D017384:Sequence Deletion; D016324:Sequence Tagged Sites; D014162:Transfection; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D000097624:Rabphilin-3A
D048868:Adaptor Proteins, Signal Transducing; D002118:Calcium; D019204:GTP-Binding Proteins; D013006:Growth Hormone; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D000097624:Rabphilin-3A