PR01368

SYNAPSIN

PRINTS entry
Member databasePRINTS
PRINTS typefamily
Short nameSYNAPSIN

Description
Imported from IPR001359

The synapsins are a family of neuron-specific phosphoproteins that coat synaptic vesicles and are involved in the binding between these vesicles and the cytoskeleton (including actin filaments). The family comprises 5 homologous proteins Ia, Ib, IIa, IIb and III. Synapsins I, II, and III are encoded by 3 different genes. The a and b isoforms of synapsin I and II are splice variants of the primary transcripts
[2]
.

Synapsin I is mainly associated with regulation of neurotransmitter release from presynaptic neuron terminals
[4]
. Synapsin II, as well as being involved in neurotransmitter release, has a role in the synaptogenesis and synaptic plasticity responsible for long term potentiation
[1]
. Recent studies implicate synapsin III with a developmental role in neurite elongation and synapse formation that is distinct from the functions of synapsins I and II
[3]
.

Structurally, synapsins are multidomain proteins, of which 3 domains are common to all the mammalian forms. The N-terminal `A' domain is ~30 residues long and contains a serine residue that serves as an acceptor site for protein kinase-mediated phosphorylation. This is followed by the `B' linker domain, which is ~80 residues long and is relatively poorly conserved. Domain `C' is the longest, spanning approximately 300 residues. This domain is highly conserved across all the synapsins (including those from Drosophila) and is possessed by all splice variants. The remaining six domains, D-I, are not shared by all the synapsins and differ both between the primary transcripts and the splice variants.

References
Imported from IPR001359

1.Essential functions of synapsins I and II in synaptic vesicle regulation. Rosahl TW, Spillane D, Missler M, Herz J, Selig DK, Wolff JR, Hammer RE, Malenka RC, Sudhof TC. Nature 375, 488-93, (1995). View articlePMID: 7777057

2.Upregulation of synapsin IIa and IIb mRNAs in the paraventricular and supraoptic nuclei in chronic salt loaded and lactating rats. Nomura M, Ueta Y, Serino R, Yamamoto Y, Shibuya I, Yamashita H. Neurosci. Res. 37, 201-10, (2000). View articlePMID: 10940454

3.Synapsin III: developmental expression, subcellular localization, and role in axon formation. Ferreira A, Kao HT, Feng J, Rapoport M, Greengard P. J. Neurosci. 20, 3736-44, (2000). PMID: 10804215

4.Intraterminal injection of synapsin I or calcium/calmodulin-dependent protein kinase II alters neurotransmitter release at the squid giant synapse. Llinas R, McGuinness TL, Leonard CS, Sugimori M, Greengard P. Proc. Natl. Acad. Sci. U.S.A. 82, 3035-9, (1985). View articlePMID: 2859595

Supplementary References

1. Neurotransmission. Keeping synapses up to speed. De Camilli P. Nature 375, 450-1, (1995). View articlePMID: 7777050

2. Distinct pools of synaptic vesicles in neurotransmitter release. Pieribone VA, Shupliakov O, Brodin L, Hilfiker-Rothenfluh S, Czernik AJ, Greengard P. Nature 375, 493-7, (1995). View articlePMID: 7777058

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