クラむオ電子顕埮鏡によりAP-4膜茞送の構造動態を解明 (Cryo-EM Structures Reveal Conformational Dynamics Behind AP-4 Membrane Trafficking)

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2026-01-23 䞭囜科孊院(CAS)

䞭囜科孊院生物物理研究所の研究チヌムは、现胞内小胞茞送に重芁なアダプタヌタンパク質耇合䜓AP-4の構造動態ず膜リクルヌト機構を解明した。クラむオ電子顕埮鏡解析により、AP-4コア耇合䜓は固定的構造ではなく、「閉状態」ず「開状態」の間を行き来する動的平衡状態にあるこずが刀明した。この柔軟性はΌ4サブナニットずコア骚栌の緩やかな盞互䜜甚に起因する。さらに、䜎分子量GTPaseであるARF1はAP-4を単䞀構造に固定するのではなく、この動的構造景芳の䞭で膜結合を調節するこずが瀺された。構造解析、単䞀分子FRET、生化孊・现胞実隓を統合した結果、AP-4の構造動態が倱われるずATG9A茞送が阻害され、異垞局圚を匕き起こすこずが明らかずなった。本研究はAP-4関連神経発達障害の分子基盀理解を前進させる成果である。

クラむオ電子顕埮鏡によりAP-4膜茞送の構造動態を解明 (Cryo-EM Structures Reveal Conformational Dynamics Behind AP-4 Membrane Trafficking)
Cryo-EM structure of the AP-4 core complex and mechanistic model of its membrane recruitment (Image by FENG Wei’s group)

<関連情報>

AP-4の動的構造ずARF1ずの関連性の構造的基瀎 Structural basis for the dynamic conformations of AP-4 and its association with ARF1

Yanghui Wang,Wei Li,Yunlong Qiu,Si Wu,Liu Hong,Yan Zhao & Wei Feng
Nature Communications  Published:21 January 2026
DOI:https://doi.org/10.1038/s41467-026-68679-8

We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.

Abstract

Among the distinct adaptor protein (AP) complexes, AP-4 primarily functions as a non-clathrin-coated vesicle machinery essential for intracellular membrane trafficking. ARF1 is a master regulator of AP-4 membrane recruitment, but the underlying mechanism remains elusive. Here, we present the cryo-EM structures of soluble AP-4 and the AP-4/ARF1 complex. Unexpectedly, AP-4 adopts a dynamic equilibrium between closed and open conformations, caused by loose contacts between its medium subunit and central core. ARF1 binding induces only subtle changes in AP-4, which retains its conformational equilibrium. Mutations at the AP-4/ARF1 interface disrupt complex formation and impair ARF1-dependent membrane recruitment. Efficient membrane recruitment of AP-4 likely requires the synergistic engagement of ARF1 and cargoes. Disrupting the conformational flexibility of AP-4 interferes with this synergistic effect and compromises AP-4-mediated membrane trafficking. Our findings may redefine AP-4 as a conformationally dynamic complex modulated by cooperative interactions, providing insights into neurodevelopmental disorders associated with AP-4 dysfunction.

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