DNA repair protein XRCC4

XRCC4
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	1FU1, 1IK9, 3II6, 3MUD, 3Q4F, 3RWR, 3SR2, 3W03, 4XA4, 5CHX, 5CJ0, 5CJ4, 5E50
Identifiers
Aliases	XRCC4, SSMED, X-ray repair complementing defective repair in Chinese hamster cells 4, X-ray repair cross complementing 4, hXRCC4
External IDs	OMIM: 194363; MGI: 1333799; HomoloGene: 2555; GeneCards: XRCC4; OMA:XRCC4 - orthologs
Gene location (Human)
Chr.	Chromosome 5 (human)
End	83,353,787 bp
Gene location (Mouse)
Chr.	Chromosome 13 (mouse)
End	90,237,727 bp
RNA expression pattern
	Top expressed in
	testicle; ; monocyte; ; gonad; ; secondary oocyte; ; ventricular zone; ; Descending thoracic aorta; ; Achilles tendon; ; ganglionic eminence; ; islet of Langerhans; ; ascending aorta;
	Top expressed in
	spermatocyte; ; spermatid; ; seminiferous tubule; ; zygote; ; secondary oocyte; ; pineal gland; ; Epithelium of choroid plexus; ; primary oocyte; ; olfactory epithelium; ; granulocyte;
	More reference expression data
	; ; ; ;
	More reference expression data
Gene ontology
Molecular function	DNA binding; ligase activity; protein C-terminus binding; protein binding; identical protein binding;
Cellular component	cytosol; nucleoplasm; DNA-dependent protein kinase-DNA ligase 4 complex; DNA ligase IV complex; nonhomologous end joining complex; condensed chromosome; nucleus;
Biological process	DNA recombination; cellular response to lithium ion; cellular response to DNA damage stimulus; establishment of integrated proviral latency; DNA ligation involved in DNA repair; positive regulation of ligase activity; double-strand break repair via nonhomologous end joining; response to X-ray; double-strand break repair; DNA repair;
	Sources:Amigo / QuickGO
Orthologs
	7518
	108138
	ENSG00000152422
	ENSMUSG00000021615
	Q13426
	Q924T3
	NM_003401; NM_022406; NM_022550; NM_001318012; NM_001318013
	NM_028012
NP_001304941; NP_001304942; NP_003392; NP_071801; NP_072044;
	NP_071801.1; NP_001304941.1; NP_001304942.1
	NP_082288
	Wikidata
View/Edit Human	View/Edit Mouse

DNA repair protein XRCC4 (hXRCC4) also known as X-ray repair cross-complementing protein 4 is a protein that in humans is encoded by the XRCC4 gene. XRCC4 is also expressed in many other animals, fungi and plants. hXRCC4 is one of several core proteins involved in the non-homologous end joining (NHEJ) pathway to repair DNA double strand breaks (DSBs).

NHEJ requires two main components to achieve successful completion. The first component is the cooperative binding and phosphorylation of artemis by the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs). Artemis cleaves the ends of damaged DNA to prepare it for ligation. The second component involves the bridging of DNA to DNA ligase 4, by hXRCC4, with the aid of Cernunnos-XLF. DNA-PKcs and hXRCC4 are anchored to Ku70 / Ku80 heterodimer, which are bound to the DNA ends.

Since hXRCC4 is the key protein that enables interaction of DNA ligase 4 to damaged DNA and therefore ligation of the ends, mutations in the XRCC4 gene were found to cause embryonic lethality in mice and developmental inhibition and immunodeficiency in humans. Furthermore, certain mutations in XRCC4 are associated with an increased risk of cancer.