Light-sensitive response in melanophores of Xenopus laevis: II.Rho is involved in light-induced melanin aggregation.
Melanophores of the isolated tail fin of the Xenopus tadpole aggregate melanin granules in response to light. This aggregation was found to be inhibited by subcutaneous injection of exoenzyme C3 of Clostridium botulinum. A 26 kDa protein in homogenate obtained from the Xenopus tail fin was ADP-ribosylated by exoenzyme C3. This reaction was inhibited effectively by a monoclonal antibody, anti-Rho mab A5. raised against the small GTP-binding protein Rho. The extent of ADP-ribosylation depended on light and guanine nucleotide. Incubation under illumination partly reduced ADP-ribosylation and the reduction was restored by addition of guanine nucleotide during incubation. These findings suggest that Rho is involved in the photo-sensitive melanophore response as a signal transducer linking photo-stimuli to melanin granule translocation with Xenopus melanophores.
Department of Biology, Faculty of Medicine, Sapporo Medical University, Japan.
Y
Y
Miyashita
T
T
Moriya
N
N
Yokosawa
S
S
Hatta
J
J
Arai
S
S
Kusunoki
S
S
Toratani
H
H
Yokosawa
N
N
Fujii
K
K
Asami
D036002:ADP Ribose Transferases / Q000494:pharmacology; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins / Q000276:immunology; D008027:Light; D008543:Melanins / Q000378:metabolism*; D008547:Melanophores / Q000187:drug effects / Q000502:physiology*; D013623:Tail / Q000737:chemistry / Q000166:cytology / Q000187:drug effects; D014982:Xenopus laevis; D020742:rhoA GTP-Binding Protein
D008543:Melanins; D000246:Adenosine Diphosphate Ribose; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein