Biomines-stimulated phosphorylation and (Na +, K +-ATPase in the gills of the chinese crab, Eriocheir sinensis

Abstract

1. 1. Subcellular distribution of (NA +, K +-ATPase and ouabain-insensitive ATPase (Mg 2+-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water. 2. 2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation. 3. 3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction. 4. 4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills. 1. (a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone. 2. (b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P 3 from the posterior gills. 3. (c) No activation occurs with the fractions P 3 as well as P 1 or P 2 (not shown) from anterior gills of fresh water crab. 4. (d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation. 5. (e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation. 6. 5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.