1,721,294 research outputs found
Synaptophysin (p38) at the frog neuromuscular junction: its incorporation into the plasma membrane and recycling after intense quantal secretion
No full textEffects of the neuronal phosphoprotein synapsin I on actin polymerization. II. Analytical interpretation of kinetic curves.
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Synapsin I, a neuron-specific phosphoprotein interacting with small synaptic vesicles and F-actin.
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Binding of synapsin i to synaptic vesicles: Clues from the study of its interactions with liposomes
No full textSynapsin I is a major brain phosphoprotein which interacts with synaptic vesicles and actin in a phosphorylation-dependent fashion. The binding of synapsin I to synaptic vesicles involves interactions with the phospholipid and protein components of the vesicle membrane. The highly hydrophobic NH2-terminal head region of the protein binds with high-affinity to acidic phospholipids and penetrates the hydrophobic core of the membrane, whereas the basic COOH-terminal tail region does not significantly contribute to this binding. The interaction with phospholipids increases the amount of αhelix in the secondary structure of synapsin I, but does not markedly affect the microenvironment of tryptophan and cysteine residues present in the head region. The results suggest that synapsin I binds to synaptic vesicle phospholipids through amphiphilic and positively charged domains present in its NH2-terminal region and that such an interaction contributes to the high-affinity binding of synapsin I to synaptic vesicles. © 1993 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted
Synapsin is a novel Rab3 effector protein on small synaptic vesicles. II. Functional effects of the Rab3A-synapsin I interaction.
No full textActivation of the cAMP/PKA/DARPP-32 signaling pathway is required for morphine psychomotor stimulation but not for morphine reward
No full textActivation of the cAMP/PKA pathway in the dopaminoceptive neurons of the striatum has been proposed to mediate the actions of various classes of drugs of abuse. Here, we show that, in the mouse nucleus accumbens and dorsal striatum, acute administration of morphine resulted in an increase in the state of phosphorylation of the dopamine- and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) at Thr34, without affecting phosphorylation at Thr75. The ability of morphine to stimulate Thr34 phosphorylation was prevented by blockade of dopamine D1 receptors. DARPP-32 knockout mice and T34A DARPP-32 mutant mice displayed a lower hyperlocomotor response to a single injection of morphine than wild-type controls. In contrast, in T75A DARPP-32 mutant mice, morphine-induced psychomotor activation was indistinguishable from that of wild-type littermates. In spite of their reduced response to the acute hyperlocomotor effect of morphine, DARPP-32 knockout mice and T34A DARPP-32 mutant mice were able to develop behavioral sensitization to morphine comparable to that of wild-type controls and to display morphine conditioned place preference. These results demonstrate that dopamine D1 receptor-mediated activation of the cAMP/DARPP-32 cascade in striatal medium spiny neurons is involved in the psychomotor action, but not in the rewarding properties, of morphine
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