Synaptojanin 2, a Novel Synaptojanin Isoform with a Distinct Targeting Domain and Expression Pattern
| Autor: | Christof Haffner, Yasuo Nemoto, Monica Arribas, Pietro DeCamilli |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Gene isoform
DNA Complementary Protein family Molecular Sequence Data Nerve Tissue Proteins CHO Cells Synaptojanin Biology Biochemistry src Homology Domains Cricetinae Phospholipase D Animals Synaptic vesicle recycling Tissue Distribution Amino Acid Sequence Enzyme Inhibitors Molecular Biology Peptide sequence Chinese hamster ovary cell Cell Biology Phosphoric Monoester Hydrolases Synaptojanin-1 Rats Cell biology Isoenzymes Molecular Weight Phosphatidylinositol-3 4 5-Trisphosphate 5-Phosphatases Amphiphysin Sequence Alignment Epitope Mapping Protein Binding |
| Zdroj: | Journal of Biological Chemistry. 272:30817-30821 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.272.49.30817 |
| Popis: | Synaptojanin (synaptojanin 1) is a recently identified inositol 5′-phosphatase, which is highly enriched in nerve terminals and is implicated in synaptic vesicle recycling. It is composed of three domains: an amino-terminal SacI homology region, a central inositol 5′-phosphatase homology region, and a carboxyl-terminal proline-rich region. We have now identified and characterized a novel form of synaptojanin, synaptojanin 2, which has a broader tissue distribution. Synaptojanin 2 cDNA from rat brain library encodes a protein of 1,248 amino acids with a predictedM r of 138,268. The two synaptojanin isoforms share 57.2 and 53.8% amino acid identity in their SacI and phosphatase domains, respectively. In marked contrast, their carboxyl-terminal proline-rich regions bear little homology. Expression of synaptojanin 2 in COS7 cells produced a 140-kDa protein with inositol 5′-phosphatase actvity. Protein binding assays demonstrated that among the major src homology 3-proteins known to bind to the proline-rich region of synaptojanin 1, Grb2, amphiphysin, and members of SH3p4/8/13 protein family, only Grb2 bound to that of synaptojanin 2. Furthermore, subcellular fractionation studies in transfected Chinese hamster ovary cells revealed that synaptojanin 2 was predominantly associated with the particulate fraction while synaptojanin 1 was mainly localized in the soluble fraction. This observation suggests that the proline-rich regions of synaptojanins 1 and 2 are implicated in different protein-protein interactions and direct the two isoforms to different subcellular compartments. Our results demonstrate the presence of a family of synaptojanin-type inositol 5′-phosphatases with different tissue and subcellular distributions, which may be involved in distinct membrane trafficking and signal transduction pathways in mammalian cells. |
| Databáze: | OpenAIRE |
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