{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nSTX4 functions as a critical t‐SNARE in regulated exocytosis across multiple cell types. In neurons, it localizes to specialized postsynaptic microdomains where it orchestrates the fusion of recycling endosomes carrying AMPA receptors, thereby contributing to dendritic spine remodeling and long‐term potentiation. In pancreatic β‐cells, STX4 is essential for glucose‐stimulated insulin release—a process influenced by posttranslational modifications such as S‑nitrosylation and phosphorylation that modulate its interaction with v‑SNARE partners and facilitate granule fusion with the plasma membrane."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "5"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nBeyond neural and endocrine functions, STX4 plays a pivotal role in vesicular trafficking that underpins secretory processes in diverse cell types. In immune and secretory cells, it mediates the final fusion step required for cytokine release in dendritic cells as well as the exocytosis of immunoglobulins from plasma cells. Moreover, STX4 is involved in the proper targeting of proteins such as dysferlin in skeletal muscle and integrins at the leading edge of migrating cells, while also demonstrating extracellular functions that influence keratinocyte differentiation."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "6", "end_ref": "11"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn the context of cell migration, invasion, and pathogenesis, STX4 facilitates the targeted delivery of membrane proteins such as MT1‑MMP to invadopodia, promoting extracellular matrix degradation and tumor cell invasion. Its role extends to the release of viral particles, as exemplified by hepatitis C virus export, and to modulating host defense mechanisms during bacterial phagocytosis. Furthermore, altered STX4 expression and regulation have been implicated in diverse disease states—including psoriasis‐associated type 2 diabetes, kidney renal clear cell carcinoma, congenital hearing impairment, and aberrant neutrophil degranulation—while its activity is finely tuned by phosphorylation events (that also regulate acid sphingomyelinase translocation) and by interactions with regulatory proteins like Munc18c. Finally, STX4’s influence on exocytosis is evident in salivary gland secretory responses, underscoring its broad physiological and pathological significance."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "12", "end_ref": "23"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Matthew J Kennedy, Ian G Davison, Camenzind G Robinson, et al. 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