<div class="infobox infobox-protein"> | | | |---|---| [@peroxisomal2021] | Protein Name | ABCD2 Protein | [@abc2018] | Gene | [ABCD2](/genes/abcd2) | [@very2022] | UniProt ID | [O14678](https://www.uniprot.org/uniprot/O14678) | | Family | ABC transporter subfamily D ( peroxisomal) | | Tissue Expression | Brain, liver, kidney, adrenal gland | </div>
Overview
ABCD2 (ATP-Binding Cassette Subfamily D Member 2) is a peroxisomal membrane protein that belongs to the ATP-binding cassette (ABC) transporter family. Like its closely related paralog [ABCD1](/genes/abcd1) (which causes [X-linked adrenoleukodystrophy](/diseases/x-linked-adrenoleukodystrophy) when mutated), ABCD2 functions as a peroxisomal importer of very long-chain fatty acids (VLCFAs) and their CoA esters. While ABCD1 is the primary peroxisomal VLCFA transporter in the brain, ABCD2 can partially compensate and has distinct expression patterns and substrate specificities.
Structure and Mechanism
ABCD2 is an integral peroxisomal membrane protein consisting of approximately 655 amino acids. Like other ABC transporters, it contains:
Two transmembrane domains (TMDs): Six transmembrane helices that form the substrate translocation pore
Two nucleotide-binding domains (NBDs): These bind and hydrolyze ATP to provide energy for transport
...
ABCD2 Protein
<div class="infobox infobox-protein"> | | | |---|---| [@peroxisomal2021] | Protein Name | ABCD2 Protein | [@abc2018] | Gene | [ABCD2](/genes/abcd2) | [@very2022] | UniProt ID | [O14678](https://www.uniprot.org/uniprot/O14678) | | Family | ABC transporter subfamily D ( peroxisomal) | | Tissue Expression | Brain, liver, kidney, adrenal gland | </div>
Overview
ABCD2 (ATP-Binding Cassette Subfamily D Member 2) is a peroxisomal membrane protein that belongs to the ATP-binding cassette (ABC) transporter family. Like its closely related paralog [ABCD1](/genes/abcd1) (which causes [X-linked adrenoleukodystrophy](/diseases/x-linked-adrenoleukodystrophy) when mutated), ABCD2 functions as a peroxisomal importer of very long-chain fatty acids (VLCFAs) and their CoA esters. While ABCD1 is the primary peroxisomal VLCFA transporter in the brain, ABCD2 can partially compensate and has distinct expression patterns and substrate specificities.
Structure and Mechanism
ABCD2 is an integral peroxisomal membrane protein consisting of approximately 655 amino acids. Like other ABC transporters, it contains:
Two transmembrane domains (TMDs): Six transmembrane helices that form the substrate translocation pore
Two nucleotide-binding domains (NBDs): These bind and hydrolyze ATP to provide energy for transport
The protein forms homodimers or heterodimers (with [ABCD1](/genes/abcd1) or [ABCD3](/genes/abcd3)) to create functional transporters. ABCD2 has preference for transporting C22-C26 very long-chain fatty acids, branched-chain fatty acids, and certain prostaglandins into the peroxisome for β-oxidation.
Expression Pattern
ABCD2 is expressed in multiple tissues with particularly high expression in:
Brain: [Neurons](/entities/neurons), [astrocytes](/entities/astrocytes), and oligodendrocytes
Liver: Hepatocytes
Kidney: Renal tubules
Adrenal gland: Cortical cells
Testis: Spermatogenic cells
Within the brain, ABCD2 expression is notable in:
Cerebral [cortex](/brain-regions/cortex) neurons
Hippocampal pyramidal neurons
Cerebellar Purkinje cells
White matter oligodendrocytes
Role in Lipid Metabolism
Peroxisomal β-Oxidation
ABCD2 plays a critical role in peroxisomal fatty acid metabolism:
Imports VLCFAs (C22-C26) into peroxisomes
Enables β-oxidation of very long-chain fatty acids
Facilitates degradation of branched-chain fatty acids (e.g., phytanic acid)
Participates in synthesis of bile acid intermediates
Relationship to ABCD1
ABCD1 and ABCD2 can form functional heterodimers. This has therapeutic implications:
Overexpression of ABCD2 can partially compensate for ABCD1 deficiency
ABCD2 has distinct substrate preferences (longer chain lengths)
Tissue-specific expression patterns differ between the two
Role in Neurodegeneration
Adrenoleukodystrophy Spectrum
While mutations in [ABCD1](/genes/abcd1) cause X-linked adrenoleukodystrophy (X-ALD), ABCD2 may modify disease severity:
ABCD2 polymorphisms may influence age of onset
ABCD2 expression can compensate for ABCD1 deficiency
Therapeutic strategies targeting ABCD2 are being explored
Peroxisomal Dysfunction in Neurodegeneration
Peroxisomal abnormalities are increasingly recognized in multiple neurodegenerative disorders:
[Unknown, The peroxisomal ABC transporter family: Emerging insights into structure and function. Current Opinion in Cell Biology, 2020 (2020)](https://doi.org/10.1016/j.ceb.2020.03.013)
[Unknown, ABCD2: A potential therapeutic target for X-linked adrenoleukodystrophy. Molecular Genetics and Metabolism, 2019 (2019)](https://doi.org/10.1016/j.ymgme.2019.02.008)
[Unknown, Peroxisomal dysfunction in neurodegenerative diseases. Acta Neuropathologica, 2021 (2021)](https://doi.org/10.1007/s00401-021-02299-y)
[Unknown, ABC transporters in neural development and neurodegeneration. Journal of Neurochemistry, 2018 (2018)](https://doi.org/10.1111/jnc.14356)
[Unknown, Very long-chain fatty acid metabolism in neurodegeneration. Biochimica et Biophysica Acta, 2022 (2022)](https://doi.org/10.1016/j.bbadis.2022.166549)