From the Research
XK Gene and McLeod Syndrome
- The XK gene is associated with the McLeod syndrome, a rare X-linked disorder characterized by hemolytic anemia, neuropsychiatric problems, and late-onset myopathy 1, 2, 3.
- Mutations in the XK gene can lead to the McLeod phenotype, which is marked by weakened expression of Kell blood group system antigens, absence of Kx and Km antigens, and acanthocytosis 1, 2, 3.
- The XK gene encodes a putative membrane transporter that is part of the XK/Kell complex of the Kell blood group system 4, 5.
Expression and Function of XK Gene
- The XK gene is ubiquitously expressed, but its substrate is unknown 4.
- The absence of the XK protein is associated with red cell acanthocytosis and late-onset central nervous system and neuromuscular abnormalities 4.
- The XK protein is linked to the Kell protein by a disulfide bond, and together they form the XK/Kell complex 5.
Related Genes and Proteins
- Two new members of the XK family, XPLAC and XTES, have been identified, which are closely related to XK and define them together as the XK family 4.
- XPLAC is expressed mostly in placenta and adrenal gland, while XTES is exclusively expressed in primate testis 4.
- The Kell protein is a member of the neprilysin (M13) family of membrane zinc endopeptidases and preferentially activates endothelin-3 by specific cleavage of the Trp21-Ile22 bond of big endothelin-3 5.