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Gene Review

Sytl4  -  synaptotagmin-like 4

Mus musculus

Synonyms: Exophilin-2, Gph, Granuphilin, Slp4, Synaptotagmin-like protein 4, ...
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High impact information on Sytl4

  • Thus, granuphilin not only is essential for the docking of insulin granules but simultaneously imposes a fusion constraint on them through an interaction with the syntaxin-1a fusion machinery [1].
  • The Rab27a effector granuphilin is specifically localized on insulin granules and is involved in their exocytosis [1].
  • The enhanced secretion in mutant beta cells is correlated with a decrease in the formation of the fusion-incompetent syntaxin-1a-Munc18-1 complex, with which granuphilin normally interacts [1].
  • Here we show that the number of insulin granules morphologically docked to the plasma membrane is markedly reduced in granuphilin-deficient beta cells [1].
  • Granuphilin modulates the exocytosis of secretory granules through interaction with syntaxin 1a [2].

Biological context of Sytl4

  • Surprisingly, despite the docking defect, the exocytosis of insulin granules in response to a physiological glucose stimulus is significantly augmented, which results in increased glucose tolerance in granuphilin-null mice [1].
  • The domain structure of the protein products of the granuphilin gene contains an amino-terminal zinc-finger motif and carboxyl-terminal C(2)-domains, similar to that of the rabphilin-3 gene [3].
  • The Slp1-3 C2 domains show high homology to granuphilin-a C2 domains, but the amino-terminal domain of Slp1-3 does not contain any known protein motifs or a transmembrane domain [4].
  • Here, we show that the granuphilin promoter is a target of SREBP-1c, a transcription factor that controls fatty acid synthesis, and MafA, a beta cell differentiation factor [5].

Anatomical context of Sytl4


Associations of Sytl4 with chemical compounds


Physical interactions of Sytl4


Regulatory relationships of Sytl4


Other interactions of Sytl4


  1. Granuphilin molecularly docks insulin granules to the fusion machinery. Gomi, H., Mizutani, S., Kasai, K., Itohara, S., Izumi, T. J. Cell Biol. (2005) [Pubmed]
  2. Granuphilin modulates the exocytosis of secretory granules through interaction with syntaxin 1a. Torii, S., Zhao, S., Yi, Z., Takeuchi, T., Izumi, T. Mol. Cell. Biol. (2002) [Pubmed]
  3. Novel rabphilin-3-like protein associates with insulin-containing granules in pancreatic beta cells. Wang, J., Takeuchi, T., Yokota, H., Izumi, T. J. Biol. Chem. (1999) [Pubmed]
  4. Synaptotagmin-like protein 1-3: a novel family of C-terminal-type tandem C2 proteins. Fukuda, M., Mikoshiba, K. Biochem. Biophys. Res. Commun. (2001) [Pubmed]
  5. Granuphilin is activated by SREBP-1c and involved in impaired insulin secretion in diabetic mice. Kato, T., Shimano, H., Yamamoto, T., Yokoo, T., Endo, Y., Ishikawa, M., Matsuzaka, T., Nakagawa, Y., Kumadaki, S., Yahagi, N., Takahashi, A., Sone, H., Suzuki, H., Toyoshima, H., Hasty, A.H., Takahashi, S., Gomi, H., Izumi, T., Yamada, N. Cell metabolism. (2006) [Pubmed]
  6. Rab27 effector granuphilin promotes the plasma membrane targeting of insulin granules via interaction with syntaxin 1a. Torii, S., Takeuchi, T., Nagamatsu, S., Izumi, T. J. Biol. Chem. (2004) [Pubmed]
  7. Slp4-a/granuphilin-a regulates dense-core vesicle exocytosis in PC12 cells. Fukuda, M., Kanno, E., Saegusa, C., Ogata, Y., Kuroda, T.S. J. Biol. Chem. (2002) [Pubmed]
  8. Slp4-a/granuphilin-a interacts with syntaxin-2/3 in a Munc18-2-dependent manner. Fukuda, M., Imai, A., Nashida, T., Shimomura, H. J. Biol. Chem. (2005) [Pubmed]
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