Structural basis of an endoplasmic reticulum EMC:Spf1 insertase-dislocase complex.

The ER membrane protein complex (EMC) forms a stoichiometric supercomplex with the P5A-ATPase Spf1/ATP13A1, positioning their insertase and dislocase sites for coordinated substrate handling.

• Why it matters: Membrane protein insertion at the ER must be quality controlled to avoid mistargeting and misfolding, but how distinct proteostasis machines coordinate at the membrane is unclear.
• What they did: Using biochemical, structural, and cellular assays plus cryo-electron microscopy, the study shows EMC and Spf1 associate stoichiometrically while keeping their separate catalytic activities and remodel the interface via Spf1’s ATPase cycle.
• The result: The cryo-EM structures place the EMC insertase cavity and Spf1 dislocase cleft near each other and show ATP-driven remodeling that changes cytoplasmic access to both substrate-binding cavities, supporting hub-like coordination for biogenesis and quality control.

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