The Ca(2+)-dependent release of neurotransmitters and neuropeptides from the presynaptic nerve terminal occupies a
central role in synaptic transmission. The basic events involved in neurotransmitter release include the mobilization,
docking, and fusion of synaptic vesicles with the presynaptic membrane. The synaptotagmins are integral membrane
proteins of synaptic vesicles thought to serve as Ca(2+) sensors in the process of vesicular trafficking and exocytosis.
General function
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Cellular localization
Plasma membrane
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Ovarian function
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Expression regulated by
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Ovarian localization
Oocyte
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Taft RA, et al 2002 reported the identification of genes encoding mouse oocyte secretory and
transmembrane proteins by a signal sequence trap.
At all stages of follicular
development, oocytes interact with surrounding granulosa cells and promote their
differentiation into the types of cells that support further oocyte growth and
developmental competence. These interactions suggest the existence of an
oocyte-granulosa cell regulatory loop that includes both secreted proteins and cell
surface receptors on both cell types. Factors involved in the regulatory loop will
therefore contain a signal sequence, which can be used to identify them through a
signal sequence trap (SST). A screen of an oocyte SST library identified three
classes of oocyte-expressed sequences: known mouse genes, sequences homologous
to known mammalian genes, and novel sequences of unknown function. Many of the
recovered genes may have roles in the oocyte-granulosa cell regulatory loop. For
several of the known mouse genes, new roles in follicular development are implied
by identification of their expression, for the first time, in the oocyte.
SYNAPTOTAGMIN 4 was found by the SST screen.