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Function

Functions both as NADH oxidoreductase and as regulator of apoptosis (PubMed:17094969, PubMed:20362274, PubMed:23217327, PubMed:33168626). In response to apoptotic stimuli, it is released from the mitochondrion intermembrane space into the cytosol and to the nucleus, where it functions as a proapoptotic factor in a caspase-independent pathway (PubMed:20362274). Release into the cytoplasm is mediated upon binding to poly-ADP-ribose chains (By similarity). The soluble form (AIFsol) found in the nucleus induces 'parthanatos' i.e. caspase-independent fragmentation of chromosomal DNA (PubMed:20362274). Binds to DNA in a sequence-independent manner (PubMed:27178839). Interacts with EIF3G, and thereby inhibits the EIF3 machinery and protein synthesis, and activates caspase-7 to amplify apoptosis (PubMed:17094969). Plays a critical role in caspase-independent, pyknotic cell death in hydrogen peroxide-exposed cells (PubMed:19418225). In contrast, participates in normal mitochondrial metabolism. Plays an important role in the regulation of respiratory chain biogenesis by interacting with CHCHD4 and controlling CHCHD4 mitochondrial import (PubMed:26004228).

Isoform 4

Has NADH oxidoreductase activity. Does not induce nuclear apoptosis.

Isoform 5

Pro-apoptotic isoform.

Involvement in disease

Combined oxidative phosphorylation deficiency 6

COXPD6

A mitochondrial disease resulting in a neurodegenerative disorder characterized by psychomotor delay, hypotonia, areflexia, muscle weakness and wasting. Some patients manifest prenatal ventriculomegaly and severe postnatal encephalomyopathy.

None

The disease is caused by variants affecting the gene represented in this entry.

Charcot-Marie-Tooth disease, X-linked recessive, 4, with or without cerebellar ataxia

CMTX4

A neuromuscular disorder characterized by progressive sensorimotor axonal neuropathy, distal sensory impairment, difficulty walking due to peripheral neuropathy and/or cerebellar ataxia, and deafness due to auditory neuropathy. Additional features include cognitive impairment, cerebellar atrophy, dysarthria, abnormal extraocular movements, tremor, dysmetria and spasticity. The age at onset ranges from infancy to young adulthood.

None

The disease is caused by variants affecting the gene represented in this entry.

Deafness, X-linked, 5, with peripheral neuropathy

DFNX5

A form of hearing loss characterized by absent or severely abnormal auditory brainstem response, abnormal middle ear reflexes, abnormal speech discrimination, loss of outer hair cell function, and cochlear nerve hypoplasia. DFNX5 patients manifest auditory neuropathy with childhood onset, associated with distal sensory impairment affecting the peripheral nervous system.

None

The disease is caused by variants affecting the gene represented in this entry.

Spondyloepimetaphyseal dysplasia, X-linked, with hypomyelinating leukodystrophy

SEMDHL

An X-linked recessive developmental disorder characterized by slowly progressive skeletal and neurologic abnormalities, including short stature, large and deformed joints, significant motor impairment, visual defects, and sometimes cognitive deficits. Affected individuals typically have normal early development in the first year or so of life, followed by development regression and the development of symptoms. Brain imaging shows white matter abnormalities consistent with hypomyelinating leukodystrophy.

None

The disease is caused by variants affecting the gene represented in this entry.

Post-translational modifications

Under normal conditions, a 54-residue N-terminal segment is first proteolytically removed during or just after translocation into the mitochondrial intermembrane space (IMS) by the mitochondrial processing peptidase (MPP) to form the inner-membrane-anchored mature form (AIFmit). During apoptosis, it is further proteolytically processed at amino-acid position 101 leading to the generation of the mature form, which is confined to the mitochondrial IMS in a soluble form (AIFsol). AIFsol is released to the cytoplasm in response to specific death signals, and translocated to the nucleus, where it induces nuclear apoptosis in a caspase-independent manner.

Ubiquitination by XIAP/BIRC4 does not lead to proteasomal degradation. Ubiquitination at Lys-255 by XIAP/BIRC4 blocks its ability to bind DNA and induce chromatin degradation, thereby inhibiting its ability to induce cell death.

Sequence similarities

Belongs to the FAD-dependent oxidoreductase family.

Tissue specificity

Expressed in all tested tissues (PubMed:16644725). Detected in muscle and skin fibroblasts (at protein level) (PubMed:23217327). Expressed in osteoblasts (at protein level) (PubMed:28842795).

Isoform 3

Brain specific.

Isoform 4

Expressed in all tested tissues except brain.

Isoform 5

Isoform 5 is frequently down-regulated in human cancers.

Cellular localization

  • Mitochondrion intermembrane space
  • Mitochondrion inner membrane
  • Cytoplasm
  • Nucleus
  • Cytoplasm
  • Perinuclear region
  • Proteolytic cleavage during or just after translocation into the mitochondrial intermembrane space (IMS) results in the formation of an inner-membrane-anchored mature form (AIFmit). During apoptosis, further proteolytic processing leads to a mature form, which is confined to the mitochondrial IMS in a soluble form (AIFsol). AIFsol is released to the cytoplasm in response to specific death signals, and translocated to the nucleus, where it induces nuclear apoptosis (PubMed:15775970). Release into the cytoplasm is mediated upon binding to poly-ADP-ribose chains (By similarity). Translocation into the nucleus is promoted by interaction with (auto-poly-ADP-ribosylated) processed form of PARP1 (PubMed:33168626). Colocalizes with EIF3G in the nucleus and perinuclear region (PubMed:17094969).
  • Isoform 3
  • Mitochondrion intermembrane space
  • Mitochondrion inner membrane
  • Has a stronger membrane anchorage than isoform 1.
  • Isoform 4
  • Mitochondrion
  • Cytoplasm
  • Cytosol
  • In pro-apoptotic conditions, is released from mitochondria to cytosol in a calpain/cathepsin-dependent manner.
  • Isoform 5
  • Cytoplasm

Alternative names

AIF, PDCD8, AIFM1, Programmed cell death protein 8

Target type

Proteins

Primary research area

Neuroscience

Molecular weight

66901Da

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Proteins & Peptides

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Species of origin

Cell Lines & Lysates

Target

Cell type

Species or organism