ISSN:
1432-136X
Keywords:
Melanophore
;
Mastoparan
;
Compound 48/80
;
GTP-binding protein
;
Goldfish,Carassius auratus
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract To investigate the functions of GTP-binding protein(s) in the melanosome-aggregating response in fish melanophores, the effects of activators of G-proteins, namely, mastoparan and compound 48/80, were examined in cultured melanophores of the balck-moor goldfish,Carassius auratus. Both mastoparan and compound 48/80 induced an approximately 40% increase in the GTP-hydrolyzing activity in the melanophore membranes compared to the basal level. In intact melanophores, these compounds inhibited the effect of 3-isobutyl-1-methylxanthine, which induced the accumulation of intracellular cAMP. Pretreatment of melanophores with pertussis toxin at 1 μg·ml-1 for 15 h attenuated the inhibitory effect of mastoparan on the accumulation of cAMP. However, pretreatment with the toxin only slightly attenuated the inhibitory effect of compound 48/80 on the accumulation of cAMP. In addition, compound 48/80 at 1 mg·ml-1 induced full aggregation of the melanosomes in melanophores, though mastoparan at 5 μmol·l-1 induced only 10–20% aggregation of melanophores. These results suggest that mastoparan and compound 48/80 can each activate the inhibitory G-protein in goldfish melanophores, which results in inhibition of adenylate cyclase activity. This signal-transduction pathway is involved in the aggregation of melanosomes in these cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02338289
Permalink
