T cell intracellular antigen-1 (TIA-1) plays a central role in stress granule (SG) formation by self-assembly via the prion-like domain (PLD). In the TIA-1 PLD, amino acid mutations associated with neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) or Welander distal myopathy (WDM), have been identified. However, how these mutations affect PLD self-assembly properties has remained elusive. In this study, we uncovered the implicit pathogenic structures caused by the mutations. NMR analysis indicated that the dynamic structures of the PLD are synergistically determined by the physicochemical properties of amino acids in units of five residues. Molecular dynamics simulations and three-dimensional electron crystallography, together with biochemical assays, revealed that the WDM mutation E384K attenuated the sticky properties, whereas the ALS mutations P362L and A381T enhanced the self-assembly by inducing β-sheet interactions and highly condensed assembly, respectively. These results suggest that the P362L and A381T mutations increase the likelihood of irreversible amyloid fibrillization after phase-separated droplet formation, and this process may lead to pathogenicity.

除草剤耐性遺伝子組換えトウモロコシGA21系統を分析対象とした新規系統特異的定量分析法を開発した．本分析法では，GA21ゲノム1ハプロイド当たり1か所のみ存在する挿入遺伝子配列と隣接するトウモロコシゲノムの境界部位をPCR反応によって増幅する．さらに，このPCR反応の増幅効率は内在性対照となるトウモロコシSSIIb 遺伝子の増幅効率と極めて近似するため，その内標比は理論値に近い値が得られた．また統計学的な分析値の評価を行った結果，本分析法はわが国の公定法に定められた他のGM定量分析法と同等以上の分析精度を示した．これら特性から，本法は多重リアルタイムPCR法による高効率的GMトウモロコシスクリーニング定量分析法に応用可能であると考えられる．

The membranes surrounding the eukaryotic cell and its organelles are continuously invaginating, budding, and undergoing membrane fusion–fission events, which enable them to perform functions not found in prokaryotic cells. In addition, organelles come into close contact with each other at membrane contact sites (MCSs), which involve many types of proteins, and which regulate the signaling and transport of various molecules. Vesicle-associated membrane protein (VAMP)-associated protein (VAP) is an important factor involved in the tethering and contact of various organelles at MCSs in almost all eukaryotes and has attracted attention for its association with various diseases, mainly neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). However, the detailed mechanism of its functional expression remains unclear. In this review, we quantitatively discuss the structural dynamics of the entire molecule, including intrinsically disordered regions and intramolecular and intermolecular interactions, focusing on the vertebrate VAP paralogs VAPA and VAPB. Molecular phylogenetic and biophysical considerations are the basis of the work.

Liquid-liquid phase separation (LLPS) is critical to the formation of membraneless organelles within cells. Monitoring the size and dynamics of LLPS droplets is essential to understanding their function. However, conventional methods, such as microscopy and dynamic light scattering (DLS), have limitations, including low throughput and complex setups. Here, we present a simple, label-free, high-throughput method for estimating droplet size using ultraviolet-visible (UV–Vis) spectra obtained using a standard microplate reader. This method is theoretically supported by Mie scattering theory. By analyzing the spectral shape and comparing it to that of glass beads of known sizes, our method enables the quantitative estimation of LLPS droplet size in a minimally invasive manner. We validated our approach using peptide droplets of known sizes, then applied it to monitor the growth of protein condensates formed by vesicle-associated membrane protein-associated protein B (VAPB). This technique offers a convenient, scalable alternative for screening LLPS dynamics in various biomolecular systems.