CD159a KLRC1(killer cell lectin-like receptor subfamily C, member 1), NKG2
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 2 glycoprotein
NK Cell
T Cell
26 / 26
43 / 43

Expression
CD159a is expressed on NK cell lines, CD8+ gd cells and on some T cell subset clones and lines.  CD159a glycoproteins are usually not expressed on the cell membrane unless expressed as disulfide-linked heterodimers covalently bonded to CD94.  Different NK cell clones may express 1 or more CD159a glycoproteins.

Structure
MOLECULAR FAMILY NAME:  Belongs to the killer cell lectin-like family.

CD159a is a single-pass type-2 233 glycoprotein.  It contains an extracellular domain which contains a C-type lectin domain, a transmembrane domain and a cytoplasmic domain with 2 ITIMs motifs.  NKG2 was originally identified as 5 closely related cDNAs like NKG2-A, NKG2-B, NKG2-C (CD159c), NKG2-D and NKG2-E.  NKG2-A and -B are alternatively spliced transcripts of the same gene.  The NKG2 family are structurally related to several other molecules such as the Ly-49 family, NKR-P1 family, CD69 and CD94.  The molecules are encoded within the mouse and/or human NK gene compexes which contribute to NK cell function (see Ly-49).  CD159a proteins are disulfide-bonded to CD94 proteins and are expressed as heterodimers on the surface of NK and some T cells.  Transfection studies suggest that CD159a glycoproteins may also be expressed as disulfide-linked homodimers.  The cytoplasmic domain of NKG2A/B has 2 I/VXYXXL motifs but these are absent from other NKG2 molecules.
 
MOLECULAR MASS
Cell Type Unreduced Reduced Comment
70 kDa NKG2A/CD94 heterodimer
43 kDa NKG2A plus 30 kDa CD94

POST-TRANSCRIPTIONAL MODIFICATION 

Alternative splicing yields 2 different isoforms.  These spliced variants differ in the presence or absence of an exon 4 sequence.  The transcript variant NKG2-A includes an exon 4 sequence and encodes a protein 18 aa longer than that from transcript variant NKG2-B.  NKG2-B lacks an exon 4 sequence and encodes a protein 18 aa shorter than that from transcript NKG2-A.

POST-TRANSLATIONAL MODIFICATION: No information. 


Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH CD159a

The complex of CD159a or CD159c with CD94 binds the MHC class I molecule HLA-E.  CD94/CD159a receptors have been implicated in the recognition of HLA-A, -B and -C, but there is currently no evidence for direct binding.  CD159a is associated with HLA-E.  A soluble form of NKG2-C binds to an unidentified ligand on K562 cells and binding is correlated with their susceptibility to NK cell lysis.  NKG2A has been shown to associate with the cytoplasmic tyrosine phosphatase SHP-1, presumably through its cytoplasmic I/VXYXXL motifs.



Function
NK cells are lymphocytes that can mediate lysis of certain tumor cells and virus-infected cells without previous activation.  They can also regulate specific humoral and cell mediated immunity.  NK cells preferentially express several calcium-dependent C-type lectins, which have been implicated in the regulation of the NK cell function.  CD159a/CD94 has been implicated in the recognition of the MHC class I HLA-E molecules in NK cells and some cytotoxic T cells.  It constitutes a potent negative regulation of NK cells and T lymphocyte activation programs and has been implicated in activation or inhibition of NK cell cytotoxicity and cytokine secretion. Whereas CD159a is inhibitory, CD159c activates NK cells.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD159a IN INTACT ANIMAL

CD159a has been investigated for association with arthritis because the gene is in the region associated with rheumatoid disease but so far results show no strong association.

Comments
MOLECULAR INTERACTIONS -
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD159a: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD159a: No information.

Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 3821P26715
NKG2PT0372P26715X54867
NKG2PT0373P26716X54868
NKG2AF023840
Antibodies

Revised June 25, 2008


Contact us: Webmaster |  509-335-9515 | Accessibility | Copyright | Policies
College of Veterinary Medicine Washington State University, Pullman, WA, 99164-7010 USA
Copyright 1995-2003 Washington State University