Linked Life Data

2512374

Source:http://linkedlifedata.com/resource/pubmed/id/2512374

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1990-1-23
pubmed:abstractText
Synapsin I, a neuron-specific, synaptic vesicle-associated phosphoprotein, is thought to play an important role in synaptic vesicle function. Recent microinjection studies have shown that synapsin I inhibits neurotransmitter release at the squid giant synapse and that the inhibitory effect is abolished by phosphorylation of the synapsin I molecule (Llinas et al., 1985). We have considered the possibility that synapsin I might modulate release by regulating the ability of synaptic vesicles to move to, or fuse with, the plasma membrane. Since it is not yet possible to examine these mechanisms in the intact nerve terminal, we have used video-enhanced microscopy to study synaptic vesicle mobility in axoplasm extruded from the squid giant axon. We report here that the dephosphorylated form of synapsin I inhibits organelle movement along microtubules within the interior of extruded axoplasm and that phosphorylation of synapsin I on sites 2 and 3 by calcium/calmodulin-dependent protein kinase II removes this inhibitory effect. Phosphorylation of synapsin I on site 1 by the catalytic subunit of cAMP-dependent protein kinase only partially reduces the inhibitory effect. In contrast to the inhibition of movement along microtubules seen within the interior of the axoplasm, movement along isolated microtubules protruding from the edges of the axoplasm is unaffected by dephospho-synapsin I, despite the fact that the synapsin I concentration is higher there. Thus, synapsin I does not appear to inhibit the fast axonal transport mechanism itself. Rather, these results are consistent with the possibility that dephospho-synapsin I acts by a crosslinking mechanism involving some component(s) of the cytoskeleton, such as F-actin, to create a dense network that restricts organelle movement. The relevance of the present observations to regulation of neurotransmitter release is discussed.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0270-6474
pubmed:author
pubmed:issnType
Print
pubmed:volume
9
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4138-49
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Phosphorylation-dependent inhibition by synapsin I of organelle movement in squid axoplasm.
pubmed:affiliation
Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York 10021.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.