CD238 KELL (Kell blood group, metalloendopeptidase)
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Lineage Restricted Molecule
Type 2 glycoprotein
Erythrocyte
Stem Cell
Red Cell
Hematopoietic Progenitor Cell
Erythroid Cell
Testis
93 / 93
200 / 200

Expression
CD238 is expressed on erythrocytes, hematopoietic progenitor and red cells and subsets of stem cells.  Expression is predominantly in erythroid tissues and also in testis.  Expression is lower in other tissues such as various parts of the brain, heart and skeletal muscle.

Structure
MOLECULAR FAMILY NAME: Belongs to the neprilysin (M13) family.

CD238 is a single-pass type 2 722 aa transmembrane glycoprotein.  It contains a 665 aa highly folded extracellular domain which contains 5 N-linked glycosylation sites, a 20 aa signal anchored transmembrane domain and a 47 aa intracellular cytoplasmic domain.  CD238 shows a high level of polymorphism which results at least 22 Kell blood group antigens some of which have distinct racial prevalence.  The glycoprotein links via a single disulfide bond to the XK membrane protein (32-37 kDa) that carries the Kx antigen and transvses the cell membrane 10 times.  The protein contains a sequence and similarity to members of the neprilysin (M13) family of zinc metallopeptidases.  

MOLECULAR MASS
Cell Type Unreduced Reduced
93 kDa

POST-TRANSCRIPTIONAL MODIFICATION: No information.

POST-TRANSLATIONAL MODIFICATION: No information.


Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH CD238: No information.

Function
CD238 acts as a zinc endopeptidase that cleaves a large intermediate precursor of endothelin-3 converting enzyme to its bioactive form which functions as a potent vasoconstrictor.  One biological function of endothelin-3 is as a potent vasoconstrictor.  Kell antibodies can suppress outgrowth of BFU-E as well as CFU-GM and CFU-Meg from purified CD34+ cells. 

BIOCHEMICAL ACTIVITY: No information.
 
DISEASE RELEVANCE AND FUNCTION OF CD238 IN INTACT ANIMAL

The McLeod phenotype is characterized by loss of the XK-protein and results in decreased expression of CD238 and is associated with the late onset of muscular dystrophy.  Erthrocytes from individuals with the McLeod phenotype have a unique morphology and are know as ancanthocytes.  CD238 null individuals are found at very low frequency in all populations and are healthly which implies alternative pathways exist for endothelin-3 activation.  Kel null erthryocytes have normal morphology.  Clinical studies found in alloimmunized pregnancies where the anemia found in the fetus or neonate is due to the suppression of erythropoeisis as well as to antibody-induced hemolysis.

Comments
MOLECULAR INTERACTIONS-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD238: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD238: No information.

Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 3792P23276
Antibodies

Revised June 25, 2008


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