Synapto-pHluorin

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Synapto-pHluorin is a reporter protein and a visual indicator for the release of a synaptic vesicle from nerve cells . In neuroscience , it is used to study the release of neurotransmitters , their transport by means of vesicles, and their recycling.

It consists of a pH- sensitive form of GFP and the membrane protein synaptobrevin . Sometimes it consists of a form of yellow fluorescent protein instead of GFP , because the pK a is higher (7.1 instead of 6.0). It is most sensitive in the pH range relevant to the acidic environment in vesicles. The change in color can only be seen several hundred milliseconds to several seconds after the vesicle has been released.

history

It was discovered by Gero Miesenböck in 1998. In 2006, an improved version called sypHy was developed by Björn Granseth's researchers, which consists of a pH-sensitive form of GFP and synaptophysin .

use

The pH value within the vesicles is low, which is why the Synapto-pHluorin is not yet fluorescent . As soon as the vesicles are released, Synapto-pHluorin enters the extracellular space where it becomes fluorescent due to the higher pH value. During the subsequent endocytosis , the pH value in the vesicles rises again. It was also used to show the release of insulin by the beta cells in the pancreas .

Individual evidence

  1. ^ Gertrude Bunt, Fred S. Wouters: Visualization of Molecular Activities Inside Living Cells with Fluorescent Labels . In: International Review of Cytology . Elsevier, 2004, ISBN 978-0-12-364641-5 , pp. 205–277 , doi : 10.1016 / s0074-7696 (04) 37005-1 ( elsevier.com [accessed June 2, 2018]).
  2. ↑ Gero Miesenböck, Dino A. De Angelis, James E. Rothman: Visualizing secretion and synaptic transmission with pH-sensitive green fluorescent proteins . In: Nature . tape 394 , no. 6689 , July 9, 1998, ISSN  0028-0836 , p. 192–195 , doi : 10.1038 / 28190 ( nature.com [accessed June 2, 2018]).
  3. ↑ Michael C. Ashby, Kyoko Ibaraki, Jeremy M. Henley: It's green outside: tracking cell surface proteins with pH-sensitive GFP . In: Trends in Neurosciences . tape 27 , no. 5 , May 2004, ISSN  0166-2236 , p. 257–261 , doi : 10.1016 / j.tins.2004.03.010 ( elsevier.com [accessed June 3, 2018]).
  4. ↑ Juan Burrone: Synaptic Physiology: Illuminating the Road Ahead . In: Current Biology . tape 15 , no. November 21 , 2005, p. R876 – R878 , doi : 10.1016 / j.cub.2005.10.025 ( elsevier.com [accessed October 19, 2019]).
  5. ↑ Björn Granseth, Benjamin Odermatt, Stephen J. Royle, Leon Lagnado: Clathrin-Mediated Endocytosis Is the Dominant Mechanism of Vesicle Retrieval at Hippocampal Synapses . In: Neuron . tape 51 , no. 6 , September 2006, ISSN  0896-6273 , p. 773–786 , doi : 10.1016 / j.neuron.2006.08.029 ( elsevier.com [accessed June 3, 2018]).
  6. ^ Sunil P. Gandhi, Charles F. Stevens: Three modes of synaptic vesicular recycling revealed by single-vesicle imaging . In: Nature . tape 423 , no. 6940 , June 2003, ISSN  0028-0836 , p. 607–613 , doi : 10.1038 / nature01677 ( nature.com [accessed June 3, 2018]).
  7. ↑ Takashi Tsuboi, Guy A. Rutter: Multiple Forms of "Kiss-and-Run" Exocytosis Revealed by Evanescent Wave Microscopy . In: Current Biology . tape 13 , no. 7 , April 2003, p. 563-567 , doi : 10.1016 / S0960-9822 (03) 00176-3 ( elsevier.com [accessed October 19, 2019]).