Fröhlich, M. | Search bioRxiv

bioRxiv2025

Distances and charges along the Orai1 nexus-TM3 interface control STIM1-binding and pore opening

Calcium (Ca2+) influx through the Ca2+ release-activated Ca2+ (CRAC) channel is triggered by binding of the Ca2+ sensor Stromal Interaction Molecule 1 (STIM1) to the pore-forming Orai1 complex, primarily to its cytosolic C-termini. These C-termini connect to the transmembrane domain (TM) 4 via the flexible nexus region, proposed to transmit the activation signal from the STIM1-binding site to the central pore via concentrically arranged TM domains. However, the conformational dynamics of the nexus-TM3 interface required for channel gating remain elusive. Here, we investigate its role using unnatural amino acid (UAA)-based photo- and chemical crosslinking at individual positions within the nexus-TM3 interface combined with conventional site-directed mutagenesis. We report that a widening of the nexus-TM3 interface is essential for STIM1-mediated pore opening, while hydrophobicity and contact distances in the upper nexus-TM3 interface fine-tune signal propagation to the pore. These findings underscore the relevance of the nexus-TM3 dynamics for proper Orai1 function.

biophysics↗

bioRxiv2022

Conceptual structure and current trends in Artificial Intelligence, Machine Learning, and Deep Learning research in sports: A bibliometric review

Artificial intelligence and its subcategories of machine learning and deep learning are gaining increasing importance and attention in the context of sports research. This has also meant that the number of corresponding publications has become complex and unmanageably large in human terms. In the current state of the research field, there is a lack of bibliometric analysis, which would prove useful for obtaining insights into the large amounts of available literature. Therefore, the present work aims to identify important research issues, elucidate the conceptual structure of the research field, and unpack the evolutionary trends and the direction of hot topics regarding key themes in the research field of artificial intelligence in sports. Using the Scopus database, 1215 documents (reviews and articles) were selected. Bibliometric analysis was performed using VOSviewer and bibliometrix R package. The main findings are as follows: (a) the literature and research interest concerning AI and its subcategories is growing exponentially; (b) the top 20 most cited works comprise 32.52% of the total citations; (c) the top 10 journals are responsible for 28.64% of all published documents; (d) strong collaborative relationships are present, as along with small, isolated collaboration networks of individual institutions; (e) the three most productive countries are China, the USA, and Germany; (f) different research themes can be characterized using author keywords with current trend topics, e.g., in the fields of biomechanics, injury prevention or prediction, new algorithms, and learning approaches. AI research activities in the fields of sports pedagogy, sports sociology, and sports economics seem to have played a subordinate role thus far. Overall, the findings of this study expand knowledge on the research situation as well as the development of research topics regarding the use of artificial intelligence in sports, and may guide researchers to identify currently relevant topics and gaps in the research.

scientific communication and education↗