"Interruptor" mestre do cérebro é verificado

Brain's Master Switch Is Verified

ScienceDaily (May 9, 2010) — The protein that has long been suspected by scientists of being the master switch allowing brains to function has now been verified by an Iowa State University researcher.

Yeon-Kyun Shin, professor of biochemistry, biophysics and molecular biology at ISU, has shown that the protein called synaptotagmin1 (Syt1) is the sole trigger for the release of neurotransmitters in the brain using this instrument that allows a new technique called single vesicle fusion method. (Credit: ISU photo by Bob Elbert)

Yeon-Kyun Shin, professor of biochemistry, biophysics and molecular biology at ISU, has shown that the protein called synaptotagmin1 (Syt1) is the sole trigger for the release of neurotransmitters in the brain.


Prior to this research, Syt1 was thought to be a part of the protein structure (not the sole protein) that triggered the release of neurotransmitters at 10 parts per million of calcium.


Shin's research is published in the current issue of the journal Science.


"Syt1 was a suspect previously, but people were not able to pinpoint that it's the real one, even though there were lots and lots of different trials," said Shin.


"In this case, we are trying to show in the laboratory that it's the real one. So we excluded everything else, and included SNARE proteins -- that's the machinery of the release, and the Syt1 is a calcium-sensing timer."

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Read more here/Leia mais aqui: Science Daily

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Science 7 May 2010:
Vol. 328. no. 5979, pp. 760 - 763
DOI: 10.1126/science.1187722

Dynamic Ca²⁺-Dependent Stimulation of Vesicle Fusion by Membrane-Anchored Synaptotagmin 1

Han-Ki Lee,^1,* Yoosoo Yang,^3,* Zengliu Su,^4,* Changbong Hyeon,⁵ Tae-Sun Lee,¹ Hong-Won Lee,¹Dae-Hyuk Kweon,³ Yeon-Kyun Shin,^4,6, Tae-Young Yoon^1,2,

In neurons, synaptotagmin 1 (Syt1) is thought to mediate the fusion of synaptic vesicles with the plasma membrane when presynaptic Ca²⁺ levels rise. However, in vitro reconstitution experiments have failed to recapitulate key characteristics of Ca²⁺-triggered membrane fusion. Using an in vitro single-vesicle fusion assay, we found that membrane-anchored Syt1 enhanced Ca²⁺ sensitivity and fusion speed. This stimulatory activity of membrane-anchored Syt1 dropped as the Ca²⁺ level rose beyond physiological levels. Thus, Syt1 requires the membrane anchor to stimulate vesicle fusion at physiological Ca²⁺ levels and may function as a dynamic presynaptic Ca²⁺ sensor to control the probability of neurotransmitter release.

¹ Department of Physics, KAIST, Daejeon 305-701, South Korea.² Institute for the BioCentury, KAIST, Daejeon 305-701, South Korea.³ Department of Genetic Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 4400-746, South Korea.⁴ Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 4152 Molecular Biology Building, Ames, IA 50011, USA.⁵ School of Computational Sciences, Korea Institute for Advanced Study, Seoul 130-722, South Korea.⁶ Division of Integrative Biosciences and Biotechnology, POSTECH, Pohang 790-784, South Korea.

^* These authors contributed equally to this work.

 To whom correspondence should be addressed. E-mail: colishin@iastate.edu (Y.-K.S.); tyyoon@kaist.ac.kr (T.-Y.Y.)

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