XK (protein)

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Structures	Swiss-model
Domains	InterPro

XK (protein)
XK (protein)
Identifiers
Symbol	XK
Alt. symbols	XKR1, Kx, X1k
NCBI gene	7504
HGNC	12811
OMIM	314850
PDB	BAE48708
RefSeq	NM_021083
UniProt	P51811
Other data
Locus	Chr. X p21.2-p21.1
Structures
Search for
Structures	Swiss-model
Domains	InterPro

XK
Identifiers
Aliases	XK, Kell blood group precursor, X-linked Kx blood group, KX, MCLDS, NA, NAC, X1k, XKR1
External IDs	OMIM: 314850; MGI: 103569; GeneCards: XK
Gene location (Human)
Chr.	X chromosome (human)
End	37,732,130 bp
Gene location (Mouse)
Chr.	X chromosome (mouse)
End	9,179,489 bp
RNA expression pattern
	Top expressed in
	trabecular bone; ; jejunal mucosa; ; mucosa of colon; ; mucosa of sigmoid colon; ; endothelial cell; ; duodenum; ; bone marrow; ; mucosa of ileum; ; middle temporal gyrus; ; Brodmann area 23;
	Top expressed in
	muscle of thigh; ; dentate gyrus of hippocampal formation granule cell; ; cerebellar cortex; ; granulocyte; ; superior frontal gyrus; ; primary visual cortex; ; ventricular zone; ; genital tubercle; ; tail of embryo; ; embryo;
	More reference expression data
	n/a
Gene ontology
Molecular function	protein binding; transporter activity;
Cellular component	integral component of membrane; plasma membrane; membrane;
Biological process	regulation of cell size; myelination; regulation of axon diameter; cellular magnesium ion homeostasis; cellular calcium ion homeostasis; skeletal muscle fiber development; amino acid transport;
	Sources:Amigo / QuickGO
Orthologs
Databases	NCBI: entry; OMA: entry
	7504
	22439
	ENSG00000047597
	ENSMUSG00000015342
	P51811
	Q9QXY7
	NM_021083
	NM_023500
	NP_066569
	NP_075989
	Wikidata
View/Edit Human	View/Edit Mouse

XK (also known as Kell blood group precursor) is a protein found on human red blood cells and other tissues which is responsible for the Kx antigen which helps determine a person's blood type.

Clinical significance

The Kx antigen plays a role in matching blood for blood transfusions.

Mutation of XK protein may lead to McLeod syndrome,^[5] a multi-system disorder characterized by hemolytic anemia, myopathy, acanthocytosis, and chorea.^[6]

XK is located on the X chromosome (cytogenetic band Xp21.1) and absence of the XK protein is an X-linked disease.^[7]

Clinical diagnostic

Clinical testing in patient care for Kx antigen follows published minimum quality and operational requirements,^[8] similar to red cell genotyping for any of the other recognized blood group systems. Molecular analysis can identify gene variants (alleles) that may affect Kx antigen expression on the red cell membrane.

Function

XK is a membrane transport protein of unknown action.^[9]

References

1 2 3 GRCh38: Ensembl release 89: ENSG00000047597 – Ensembl, May 2017
1 2 3 GRCm38: Ensembl release 89: ENSMUSG00000015342 – Ensembl, May 2017
↑ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
↑ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
↑ Arnaud L, Salachas F, Lucien N, Maisonobe T, Le Pennec PY, Babinet J, et al. (March 2009). "Identification and characterization of a novel XK splice site mutation in a patient with McLeod syndrome". Transfusion. 49 (3): 479–484. doi:10.1111/j.1537-2995.2008.02003.x. PMID 19040496. S2CID 27198922.
↑ Malandrini A, Fabrizi GM, Truschi F, Di Pietro G, Moschini F, Bartalucci P, et al. (June 1994). "Atypical McLeod syndrome manifested as X-linked chorea-acanthocytosis, neuromyopathy and dilated cardiomyopathy: report of a family". Journal of the Neurological Sciences. 124 (1): 89–94. doi:10.1016/0022-510X(94)90016-7. PMID 7931427. S2CID 27859436.
↑ Ho MF, Monaco AP, Blonden LA, van Ommen GJ, Affara NA, Ferguson-Smith MA, et al. (February 1992). "Fine mapping of the McLeod locus (XK) to a 150-380-kb region in Xp21". American Journal of Human Genetics. 50 (2): 317–330. PMC 1682457. PMID 1734714.
↑ Standards for Molecular Testing for Red Cell, Platelet, and Neutrophil Antigens (7 ed.). Association for the Advancement of Blood & Biotherapies. January 1, 2025. ISBN 978-1-56395-516-7.
↑ Jung HH, Russo D, Redman C, Brandner S (October 2001). "Kell and XK immunohistochemistry in McLeod myopathy". Muscle & Nerve. 24 (10): 1346–1351. doi:10.1002/mus.1154. PMID 11562915. S2CID 44749645.

External links

GeneReviews/NCBI/NIH/UW entry on McLeod Neuroacanthocytosis Syndrome
XK at BGMUT Blood Group Antigen Gene Mutation Database at NCBI, NIH
XK+protein,+human at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

[refGRCh38Ensembl-1] 1 2 3 GRCh38: Ensembl release 89: ENSG00000047597 – Ensembl, May 2017

[refGRCm38Ensembl-2] 1 2 3 GRCm38: Ensembl release 89: ENSMUSG00000015342 – Ensembl, May 2017

[3] "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.

[4] "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.

[pmid19040496-5] Arnaud L, Salachas F, Lucien N, Maisonobe T, Le Pennec PY, Babinet J, et al. (March 2009). "Identification and characterization of a novel XK splice site mutation in a patient with McLeod syndrome". Transfusion. 49 (3): 479–484. doi:10.1111/j.1537-2995.2008.02003.x. PMID 19040496. S2CID 27198922.

[6] Malandrini A, Fabrizi GM, Truschi F, Di Pietro G, Moschini F, Bartalucci P, et al. (June 1994). "Atypical McLeod syndrome manifested as X-linked chorea-acanthocytosis, neuromyopathy and dilated cardiomyopathy: report of a family". Journal of the Neurological Sciences. 124 (1): 89–94. doi:10.1016/0022-510X(94)90016-7. PMID 7931427. S2CID 27859436.

[7] Ho MF, Monaco AP, Blonden LA, van Ommen GJ, Affara NA, Ferguson-Smith MA, et al. (February 1992). "Fine mapping of the McLeod locus (XK) to a 150-380-kb region in Xp21". American Journal of Human Genetics. 50 (2): 317–330. PMC 1682457. PMID 1734714.

[8] Standards for Molecular Testing for Red Cell, Platelet, and Neutrophil Antigens (7 ed.). Association for the Advancement of Blood & Biotherapies. January 1, 2025. ISBN 978-1-56395-516-7.

[9] Jung HH, Russo D, Redman C, Brandner S (October 2001). "Kell and XK immunohistochemistry in McLeod myopathy". Muscle & Nerve. 24 (10): 1346–1351. doi:10.1002/mus.1154. PMID 11562915. S2CID 44749645.

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Blood transfusion and transfusion medicine
Blood products	Whole blood Platelets Platelet transfusion Red blood cells Plasma Fresh frozen plasma PF24 Cryoprecipitate Cryosupernatant White blood cells Granulocyte transfusion Blood substitutes
General concepts	Blood bank Blood donation Blood management International Society of Blood Transfusion ISBT 128 Red cell genotyping
Methods	Apheresis (plasmapheresis, plateletpheresis, leukapheresis) Exchange transfusion Intraoperative blood salvage
Tests	Blood compatibility testing Cross-matching Coombs test Kleihauer–Betke test Antibody elution Monocyte monolayer assay
Transfusion reactions and adverse effects	Transfusion hemosiderosis Transfusion related acute lung injury Transfusion associated circulatory overload Transfusion-associated graft versus host disease Febrile non-hemolytic transfusion reaction Hemolytic reaction acute delayed Serum sickness Transfusion transmitted infection
Blood group systems	Blood types ABO Secretor status Augustine CD59 Chido-Rodgers Colton Cromer Diego Dombrock Duffy Er FORS Gerbich GIL GLOB Hh Ii Indian JR JMH KANNO Kell (Xk) Kidd Knops Lan Lewis Lutheran LW MNS OK P1PK Raph Rh and RHAG Scianna Sid T-Tn Vel Xg Yt Other