Leukocyte immunoglobulin-like receptor subfamily A member 3 (LILR-A3) also known as CD85 antigen-like family member E (CD85e), immunoglobulin-like transcript 6 (ILT-6), and leukocyte immunoglobulin-like receptor 4 (LIR-4) is a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that in humans is encoded by the LILRA3 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

 located within the eukocyte receptor

Leukocyte immunoglobulin-like receptors

The leukocyte immunoglobulin-like receptors are a family of receptors possessing extracellular immunoglobulin domains.They are also known as CD85, ILTs and LIR, and can exert immunomodulatory effects on a wide range of immune cells...

 complex on chromosome 19q13.4. Unlike many of its family, LILRA3 lacks a transmembrane domain. The function of LILRA3 is currently unknown. however it is highly homologous to other LILR genes, and can bind human leukocyte antigen

Human leukocyte antigen

The human leukocyte antigen system is the name of the major histocompatibility complex in humans. The super locus contains a large number of genes related to immune system function in humans. This group of genes resides on chromosome 6, and encodes cell-surface antigen-presenting proteins and...

 (HLA) class I. Therefore, if secreted, the LILRA3 might impair interactions of membrane-bound LILRs (such as LILRB1

LILRB1

Leukocyte immunoglobulin-like receptor subfamily B member 1 is a protein that in humans is encoded by the LILRB1 gene.-Further reading:...

, an inhibitory receptor expressed on effector and memory CD8 T cells

Cytotoxic T cell

A cytotoxic T cell belongs to a sub-group of T lymphocytes that are capable of inducing the death of infected somatic or tumor cells; they kill cells that are infected with viruses , or are otherwise damaged or...

) with their HLA ligands, thus modulating immune reactions and influencing susceptibility to disease.

Like the closely related LILRA1, LILRA3 binds to both normal and 'unfolded' free heavy chains of HLA class I, with a preference for free heavy chains of HLA-C alleles