| PADI4 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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| Aliases | PADI4 , PAD, PAD4, PADI5, PDI4, PDI5, peptidyl arginine deiminase 4 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 605347 MGI: 1338898 HomoloGene: 7883 GeneCards: PADI4 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| EC number | 3.5.3.15 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Protein-arginine deiminase type-4, is a human protein which in humans is encoded by the PADI4 gene. [5] [6] The protein as an enzyme, specifically protein-arginine deiminase, a type of hydrolase.
The human gene is found on the short arm of Chromosome 1 near the telomere (1p36.13). It is located on the Watson (plus) strand and is 55,806 bases long. The protein is 663 amino acids long with a molecular weight of 74,095 Da. [5]
This gene is a member of a gene family which encodes enzymes responsible for the conversion of arginine to citrulline residues (citrullination). This gene may play a role in granulocyte and macrophage development leading to inflammation and immune response. [6] PADI4 plays a role in the epigenetics, [7] the deimination of arginines on histones H3 and H4 can act antagonistically to arginine methylation. [8]
The protein may be found in oligomers and binds 5 calcium ions per subunit. It catalyses the reaction:
It is normally found in the cytoplasm, nucleus and in cytoplasmic granules of eosinophils and neutrophils. It is not expressed in peripheral monocytes or lymphocytes. It is also expressed in rheumatoid arthritis synovial tissues.
In biology, histones are highly basic proteins abundant in lysine and arginine residues that are found in eukaryotic cell nuclei and in most Archaeal phyla. They act as spools around which DNA winds to create structural units called nucleosomes. Nucleosomes in turn are wrapped into 30-nanometer fibers that form tightly packed chromatin. Histones prevent DNA from becoming tangled and protect it from DNA damage. In addition, histones play important roles in gene regulation and DNA replication. Without histones, unwound DNA in chromosomes would be very long. For example, each human cell has about 1.8 meters of DNA if completely stretched out; however, when wound about histones, this length is reduced to about 90 micrometers (0.09 mm) of 30 nm diameter chromatin fibers.
Histone methyltransferases (HMT) are histone-modifying enzymes, that catalyze the transfer of one, two, or three methyl groups to lysine and arginine residues of histone proteins. The attachment of methyl groups occurs predominantly at specific lysine or arginine residues on histones H3 and H4. Two major types of histone methyltranferases exist, lysine-specific and arginine-specific. In both types of histone methyltransferases, S-Adenosyl methionine (SAM) serves as a cofactor and methyl donor group.
The genomic DNA of eukaryotes associates with histones to form chromatin. The level of chromatin compaction depends heavily on histone methylation and other post-translational modifications of histones. Histone methylation is a principal epigenetic modification of chromatin that determines gene expression, genomic stability, stem cell maturation, cell lineage development, genetic imprinting, DNA methylation, and cell mitosis.
Citrullination or deimination is the conversion of the amino acid arginine in a protein into the amino acid citrulline. Citrulline is not one of the 20 standard amino acids encoded by DNA in the genetic code. Instead, it is the result of a post-translational modification. Citrullination is distinct from the formation of the free amino acid citrulline as part of the urea cycle or as a byproduct of enzymes of the nitric oxide synthase family.
Histone-modifying enzymes are enzymes involved in the modification of histone substrates after protein translation and affect cellular processes including gene expression. To safely store the eukaryotic genome, DNA is wrapped around four core histone proteins, which then join to form nucleosomes. These nucleosomes further fold together into highly condensed chromatin, which renders the organism's genetic material far less accessible to the factors required for gene transcription, DNA replication, recombination and repair. Subsequently, eukaryotic organisms have developed intricate mechanisms to overcome this repressive barrier imposed by the chromatin through histone modification, a type of post-translational modification which typically involves covalently attaching certain groups to histone residues. Once added to the histone, these groups elicit either a loose and open histone conformation, euchromatin, or a tight and closed histone conformation, heterochromatin. Euchromatin marks active transcription and gene expression, as the light packing of histones in this way allows entry for proteins involved in the transcription process. As such, the tightly packed heterochromatin marks the absence of current gene expression.
Protein arginine N-methyltransferase 1 is an enzyme that in humans is encoded by the PRMT1 gene. The HRMT1L2 gene encodes a protein arginine methyltransferase that functions as a histone methyltransferase specific for histone H4.
In enzymology, a protein-arginine deiminase (EC 3.5.3.15) is an enzyme that catalyzes a form of post translational modification called arginine de-imination or citrullination:
Histone H2A type 2-C is a protein that in humans is encoded by the HIST2H2AC gene.
Histone H2A type 1-C is a protein that in humans is encoded by the HIST1H2AC gene.
Histone H2A type 1-H is a protein that in humans is encoded by the HIST1H2AH gene.
Histone H2A type 1-B/E is a protein that in humans is encoded by the HIST1H2AB gene.
Histone H2A type 3 is a protein that in humans is encoded by the HIST3H2A gene.
Protein-arginine deiminase type-2 is an enzyme that in humans is encoded by the PADI2 gene.
Histone H2A type 1-A is a protein that in humans is encoded by the HIST1H2AA gene.
Peptidyl arginine deiminase, type III, also known as PADI3, is a protein which in humans is encoded by the PADI3 gene.
Peptidyl arginine deiminase, type I, also known as PADI1, is a protein which in humans is encoded by the PADI1 gene.
Histone H2A type 2-B is a protein that in humans is encoded by the HIST2H2AB gene.
Anti-citrullinated protein antibodies (ACPAs) are autoantibodies that are directed against peptides and proteins that are citrullinated. They are present in the majority of patients with rheumatoid arthritis. Clinically, cyclic citrullinated peptides (CCP) are frequently used to detect these antibodies in patient serum or plasma.
H3K4me3 is an epigenetic modification to the DNA packaging protein Histone H3 that indicates tri-methylation at the 4th lysine residue of the histone H3 protein and is often involved in the regulation of gene expression. The name denotes the addition of three methyl groups (trimethylation) to the lysine 4 on the histone H3 protein.
H3R17me2 is an epigenetic modification to the DNA packaging protein histone H3. It is a mark that indicates the di-methylation at the 17th arginine residue of the histone H3 protein. In epigenetics, arginine methylation of histones H3 and H4 is associated with a more accessible chromatin structure and thus higher levels of transcription. The existence of arginine demethylases that could reverse arginine methylation is controversial.
H3R2me2 is an epigenetic modification to the DNA packaging protein histone H3. It is a mark that indicates the di-methylation at the 2nd arginine residue of the histone H3 protein. In epigenetics, arginine methylation of histones H3 and H4 is associated with a more accessible chromatin structure and thus higher levels of transcription. The existence of arginine demethylases that could reverse arginine methylation is controversial.
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