Lymphocyte-activation gene 3, also known as LAG3, 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...

 which in humans is encoded by the LAG3 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...

. LAG3 has also recently been designated CD223 (cluster of differentiation

Cluster of differentiation

The cluster of differentiation is a protocol used for the identification and investigation of cell surface molecules present on white blood cells, providing targets for immunophenotyping of cells...

 223).

Lymphocyte-activation protein 3 belongs to immunoglobulin

Immunoglobulin superfamily

The immunoglobulin superfamily is a large group of cell surface and soluble proteins that are involved in the recognition, binding, or adhesion processes of cells. Molecules are categorized as members of this superfamily based on shared structural features with immunoglobulins ; they all possess a...

 (Ig) superfamily and contains 4 extracellular Ig-like domains. The LAG3 gene contains 8 exon

Exon

An exon is a nucleic acid sequence that is represented in the mature form of an RNA molecule either after portions of a precursor RNA have been removed by cis-splicing or when two or more precursor RNA molecules have been ligated by trans-splicing. The mature RNA molecule can be a messenger RNA...

s. The sequence data, exon/intron

Intron

An intron is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene. The term intron refers to both the DNA sequence within a gene, and the corresponding sequence in RNA transcripts. Sequences that are joined together in the final...

 organization, and chromosomal localization all indicate a close relationship of LAG3 to CD4

CD4

CD4 is a glycoprotein expressed on the surface of T helper cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and was originally known as leu-3 and T4 before being named CD4 in 1984...

.