Interaction with AK2A links AIFM1 to cellular energy metabolism.

Apoptosis-inducing factor 1 (AIFM1) is a flavoprotein essential for mitochondrial function and biogenesis. Its interaction with MIA40/CHCHD4, the central component of the mitochondrial disulfide relay, accounts for some, but not all, aspects of AIFM1 function. We provide a high-confidence AIFM1 interactome that elucidates functional partners within the mitochondrial intermembrane space.

Interaction with the cysteine-free protein HAX1 expands the substrate specificity and function of MIA40 beyond protein oxidation.

The mitochondrial disulphide relay machinery is essential for the import and oxidative folding of many proteins in the mitochondrial intermembrane space. Its core component, the import receptor MIA40 (also CHCHD4), serves as an oxidoreductase but also as a chaperone holdase, which initially interacts with its substrates non-covalently before introducing disulphide bonds for folding and retaining proteins in the intermembrane space. Interactome studies have identified diverse substrates of MIA40, among them the intrinsically disordered HCLS1-associated protein X-1 (HAX1).

Approaches for the analysis of redox-dependent protein import into mitochondria of mammalian cells.

Oxidation of cysteine residues in proteins can take place as part of an enzymatic reaction cycle, during oxidative protein folding or as a consequence of redox signalling or oxidative stress. Following changes in protein thiol redox states allows to investigate the mechanisms underlying thiol-disulphide redox processes. In this book chapter, we provide information and protocols on different methods for redox state determination with a focus on these processes in the context of oxidation-dependent protein import into the mitochondrial intermembrane space.

AP-2 reduces amyloidogenesis by promoting BACE1 trafficking and degradation in neurons.

Cleavage of amyloid precursor protein (APP) by BACE-1 (β-site APP cleaving enzyme 1) is the rate-limiting step in amyloid-β (Aβ) production and a neuropathological hallmark of Alzheimer's disease (AD). Despite decades of research, mechanisms of amyloidogenic APP processing remain highly controversial. Here, we show that in neurons, APP processing and Aβ production are controlled by the protein complex-2 (AP-2), an endocytic adaptor known to be required for APP endocytosis.