This protein can help us think. Or it can shred our cells.

San Diego – A new study reveals that a protein long known to play a role in communication between cells in the brain is also capable of obliterating cells if left unchecked because of its penchant for twisting and puncturing the cell membranes.

The protein — known as complexin — if left alone is so toxic it can shred cells. Yet, in the brain, a suite of controls makes sure the protein plays nice and helps neurons communicate by aiding in the release of neurotransmitters.

The findings are published Feb. 7 in Nature Structural and Molecular Biology. "We argue that’s the most interesting membrane fusion event in our bodies, because it’s the one that underlies this conversation. It controls remembering and forgetting. It is everything," says Ed Chapman, professor of neuroscience at the University of Wisconsin School of Medicine and Public Health. "Yet to this day, nobody knows just how the proteins involved in this process really work."

In trying to better understand these proteins Chapman's lab and their collaborators discovered the surprising power of complexin. They found that it dramatically bends and reorders membranes. Live videos show the protein pinching off small bubbles of membrane while simultaneously poking holes in them.  Ultrahigh-resolution 3D images produced by the laboratories of Dorit Hanein and Niels Volkmann at the Scintillon Institute in San Diego also revealed, directly through Cryo-EM imaging, that complexin induces the formation of twisting curlicues of broken-apart membranes.

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Recent advances in structural biology research by Scintillon researchers

Left: high-resolution density;  Top: atomic model of interface; Right: conserved footprint on actin; Center phylogenetic tree of myosin.

Rapid tool for cell nanoarchitecture integrity assessment

Detailed three-dimensional contextual information of molecular processes is often necessary to understand these processes well enough to develop efficient drug-targeting and disease intervention strategies in all medical fields. We developed a tool that significantly accelerates studies providing such information (Gaietta et al., 2021 Journal of Structural Biology).

Structural basis of aE-catenin–F-actin catch bond behavior

A better understanding of how cell-cell contacts are maintained or broken is essential for unraveling the detailed mechanism of cancer progression. For example, cells need to detach to become metastatic and need to maintain contacts within a tumor. Our study significantly deepened our understanding of how cell-cell contacts work and thus potentially opens new opportunities for medical intervention in cancer progression (Xu et al., 2020 eLife).

The actomyosin interface contains an evolutionary conserved core and an ancillary interface involved in specificity

The knowledge obtained in our study has direct impact on drug-targeting strategies for malaria by telling researchers which regions of the interface are promising targets for disrupting the function of the malaria proteins while, at the same time, minimizing the potential of disrupting human protein interaction, thus preventing potential side effects (Robert-Paganin et al., 2021 Nature Communications).

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International Conference on Three-dimensional Cryo-EM Image Analysis

The 4th International Conference on Three-dimensional Cryo-EM Image Analysis will be held March 9-12, 2022, at Granlibakken Conference Center, Lake Tahoe, California. The 2022 conference builds on our successful previous events on the same theme in 2014, 2016 and 2018. This year the conference is organized by Scintillon Professors Dorit Hanein and Niels Volkmann.

The goal of this series of meetings is for technical discussions of state-of-the-art image analysis approaches and algorithm developments to tackle challenging biological problems and to identify current limitations in the field. We have recruited an outstanding panel of speakers with topics at the 2022 meeting to include: tomography and high resolution subtomogram averaging, conformational variability, deep learning, model-based refinement, and automation.  In addition, there will be a dedicated session for selected poster talks.  All sessions will focus on interactive discussions with plenty of time for questions. The preliminary program and registration details can be found at

Dorit Hanein, CHAIR & Steven Ludtke, Co-CHAIR
ORGANIZING COMMITTEE: Masahide Kikkawa,  Jose Maria Carazo, Scott Stagg, Niels Volkmann, Ed Egelman

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A brain network that curbs the urge to eat

Scintillon Institute researchers uncover an evolutionarily conserved brain region that puts a “brake” on food intake which may advance therapeutics for obesity and related disorders with excessive eating such as Prader-Willi syndrome.

Do you ever wonder why you stop eating even when there are appealing foods available?

summary of cerebellar feeding network.

The cerebellum compares hunger state with after-eating nutritional status in the gut to regulate dopamine reward signals in the striatum to control meal size. click here for higher-res image credit: Aloysius Y. T. Low

A multi-institution collaboration led by Associate Professor Albert I. Chen at the Scintillon Institute, Assistant Professor J. Nicholas Betley and Postdoctoral Fellow Aloysius Low at the University of Pennsylvania searched for brain regions that might provide a stop signal for feeding and identified the cerebellum, a brain region outside of the conventional feeding network, as an important regulator of meal size. Neural activity of this region directs the suppression of food intake in mice, and this activity is abolished in human subjects with insatiable appetite. Their findings were published in the journal Nature on November 17, 2021.

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Scintillon Institute Investigator Awarded NIH R35 Early-Career Grant

Metabolism or the set of life-sustaining chemical reactions defines the very wellbeing of humans. But can we better understand how cellular metabolism goes awry in various human diseases? The National Institute of General Medical Sciences just granted Scintillon’s Dr. Valentin Cracan $2.4 million to find out more!


The National Institute of General Medical Sciences (NIGMS) has recognized Dr. Valentin Cracan as one of the nation’s highly talented and promising scientists to receive a Maximizing Investigators’ Research Award for Early-Stage Investigators (R35 MIRA-ESI).  This grant provides about $2.4 million over five years to support the ongoing work at the Cracan’s lab that has received a number of NIH grants already since it was established about 3 years ago. We spoke with Valentin as we were interested in his research in the context of his new, special grant. 



Valentin received his undergraduate degree in Biology and Biochemistry from the Moldova State University in the Republic of Moldova in 2005 and his Ph.D. in Biological Chemistry from University of Michigan in 2012, where he studied the intracellular pathway for trafficking of vitamin B12 (cobalamin) in the laboratory of Professor Ruma Banerjee.  While in graduate school, Valentin significantly contributed to our understanding of vitamin B12-dependent cell metabolism. In 2012, he joined the laboratory of Professor Vamsi Mootha at the Massachusetts General Hospital and Harvard Medical School. There, he obtained further training in studying mitochondria, the energy factories of our cells and major hubs of cellular metabolism. In the winter of 2018, Valentin joined the Scintillon Institute faculty as an Assistant Professor.

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