Proximity-labeling-BioID-APEX

Proximity labeling (BioID / APEX / TurboID)

一行要約

Proximity labeling は engineered enzyme (BioID / TurboID = biotin ligase, APEX = peroxidase) を bait protein / 細胞内コンパートメントに融合し、近傍 (10-20 nm) のタンパク質を biotin で共有結合的にタグ付け → streptavidin pulldown + LC-MS で同定する in vivo interactome mapping 手法。Y2H / IP-MS では捉えられない transient interaction や organelle proteome を解像し、EV biogenesis, signaling complex, BBB transporter, secretome biology 等で活用。

原理

(1) BioID / TurboID: bait に融合した biotin ligase が周囲 protein の lysine residue を biotinylate (BioID = 18-24 h, TurboID = 10 min, miniTurbo = small variant)。(2) APEX2: H₂O₂ + biotin-phenol で 1 min 内に近傍を biotinylate (短時間 / 高解像度、空間 / 時間 dynamics 解析)。(3) cell lysis → streptavidin bead pulldown → tryptic digestion → LC-MS/MS → MaxQuant / FragPipe で interactor 同定。control (Mock / 無 bait) との SILAC / TMT 比較で specific interactor を選定。

サブセット: AirID = ancestral 由来高効率 ligase、PUP-IT = pupylation 依存 (low-stringency)、Split-BioID = 2 hybrid 様 conditional labeling。

主要エビデンス / 適用領域

• EV biogenesis interactome: ESCRT / syntenin / ALIX / TSG101 周辺 protein の cargo selection 機構
• Signaling complex: EGFR / KRAS / MET 等 driver tyrosine kinase の動的 interactome
• BBB transporter: BCRP / P-gp 周辺の規制タンパク同定 (CNS drug delivery 設計)
• Secretome / surfaceome: 細胞表面 / 細胞外への labeling で extracellular interactome 解析
• Subcellular proteome: mitochondrial outer membrane / nuclear pore / cilium 等の compartment 特異的プロテオーム
• Drug target deconvolution: drug-target binding 後の near-neighbor profiling

適用分野と限界

• 強み: in vivo / live cell, transient interaction 検出, organelle / spatial 解像, IP-MS で失われる弱結合保存
• 限界: bait fusion で機能変化リスク, biotin endogenous background, 近傍 = 直接結合ではない, sample prep / pulldown / MS の technical complexity, false-positive (random proximity) 補正の必要

Open Questions

• In vivo (animal) での efficient labeling
• Spatial / temporal dynamics: APEX 短時間 labeling での signaling kinetics 解析
• Quantitative interactome: SILAC / TMT 標準化と reproducibility
• EV cargo selection: proximity labeling で EV biogenesis machinery と cargo の coupling を解明

関連エンティティ

• 補完手法: Proteomics-mass-spec / CRISPR-screen / scRNA-seq / EV-isolation-characterization
• 関連遺伝子: ALIX / TSG101 / Syntenin / CD63 / CD81 / CD9
• 関連経路: Exosome-biogenesis-pathway / EGFR-signaling-pathway / RAS-GTPase-cycle-pathway
• 関連概念: Tumor-derived-EV-cargo-biology / EV-mediated-intercellular-communication

関連論文

Basic-Brain metastasis

• Hill et al. NatCommun 2025 — Molecular profiling of brain endothelial cell to astrocyte endfoot communication in mouse and human

Basic-Extracellular vesicles

• Heusermann et al. JCellBiol 2016 — Exosomes surf on filopodia to enter cells at endocytic hot spots, traffic within endosomes, and are targeted to the ER
• Choi et al. JExtracellVesicles 2012 — Quantitative proteomics of extracellular vesicles derived from human primary and metastatic colorectal cancer cells
• Sriwastva et al. JExtracellVesicles 2023 — An extracellular vesicular mutant KRAS-associated protein complex promotes lung inflammation and tumor growth
• Leidal et al. NatCellBiol 2020 — The LC3-conjugation machinery specifies the loading of RNA-binding proteins into extracellular vesicles
• Rak et al. NatCellBiol 2020 — L(C3)icensing of exosomes for RNA export

Basic-Neutrophil and myeloid cell

• Xu et al. bioRxiv 2026 — Neutrophils repurpose the nucleolus as a cytokine reservoir and secretory organelle

Basic-Oncogene and genetics

• Wang et al. SignalTransductTargetTher 2026 — Disrupting SOX2 self-association and condensate formation to overcome chemotherapeutic drug resistance in lung squamous

Basic-Others

• Menendez-Montes et al. Nature 2026 — Mitochondria directly interact with the nuclear pore complex
• Koh et al. ProcNatlAcadSciUSA 2021 — A short ORF-encoded transcriptional regulator