Mast cell degranulating (MCD) peptide and its optical isomer activate GTP binding protein in rat mast cells.
The MCD peptide in bee venom induces degranulation in mast cells. The internal calcium concentration of mast cells increased and remained high following MCD stimulation. This calcium increase was blocked by pertussis toxin (Ptx) treatment, suggesting that MCD peptide activates Ptx-sensitive G-protein. Even in the absence of external calcium in the incubation medium, the calcium concentration increased by MCD treatment, but soon returned to the original level. D-MCD, the optical isomer of the MCD peptide, also increased the internal calcium concentration through a Ptx-sensitive pathway. We suggest that cationic clusters at one side of the surface are more important in activating the G-protein than the alpha-helix conformation.
Fujimoto
I
I
Institute for Protein Research, Osaka University, Yamadaoka Suita, Japan.
Ikenaka
K
K
Kondo
T
T
Aimoto
S
S
Kuno
M
M
Mikoshiba
K
K
D000818:Animals; D002118:Calcium / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000502:physiology; D005456:Fluorescent Dyes; D016257:Fura-2; D019204:GTP-Binding Proteins / Q000502:physiology*; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D010455:Peptides / Q000494:pharmacology*; D037342:Pertussis Toxin; D051381:Rats; D011919:Rats, Inbred Strains; D013237:Stereoisomerism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D005456:Fluorescent Dyes; D010455:Peptides; D010566:Virulence Factors, Bordetella; C008331:mast cell degranulating peptide; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D002118:Calcium; D016257:Fura-2