Killer cell lectin-like receptor subfamily G member 1 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that in humans is encoded by the ''KLRG1''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
Function
Natural killer (NK) cells are
lymphocyte
A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include T cells (for cell-mediated and cytotoxic adaptive immunity), B cells (for humoral, antibody-driven adaptive immunity), an ...
s 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. The protein encoded by this gene belongs to the killer cell lectin-like receptor (KLR) family, which is a group of transmembrane proteins preferentially expressed in NK cells. Studies in mice suggested that the expression of this gene may be regulated by MHC class I molecules.
KLRG1 is a lymphocyte co-inhibitory, or immune checkpoint, receptor expressed predominantly on late-differentiated effector and effector memory CD8+ T and NK cells. Its ligands are
E-cadherin
Cadherin-1 or Epithelial cadherin (E-cadherin), is a protein that in humans is encoded by the ''CDH1'' gene (not to be confused with the APC/C activator protein CDH1). Mutations are correlated with Hereditary diffuse gastric cancer, gastric, Here ...
and
N-cadherin
Cadherin-2 also known as Neural cadherin (N-cadherin), is a protein that in humans is encoded by the ''CDH2'' gene. CDH2 has also been designated as CD325 (cluster of differentiation 325).
Cadherin-2 is a transmembrane protein expressed in multi ...
with similar affinities,
respective markers of epithelial and mesenchymal cells.
Targeting of other co-inhibitory receptors for applications in oncology has gained widespread interest
(e.g., CTLA-4, PD-1, and its ligand PD-L1). Unlike the obvious enhanced immune activation present in CTLA-4 and PD-1 gene knockout mice,
KLRG1 knockout mice initially were found to have no abnormal features,
though were subsequently found to have enhanced immunity in a tuberculosis challenge model.
The characterization of KLRG1 as a “senescent” marker, but other co-inhibitory receptors as “exhaustion” markers,
has contributed to relatively fewer studies on this molecule.
References
Further reading
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External links
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* {{PDBe-KB2, Q96E93, Killer cell lectin-like receptor subfamily G member 1