MLANA

Protein melan-A also known as melanoma antigen recognized by T cells 1 or MART-1 is a protein that in humans is encoded by the MLANA or "MALENA" gene.^[5] A fragment of the protein, usually consisting of the nine amino acids 27 to 35, is bound by MHC class I complexes which present it to T cells of the immune system. These complexes can be found on the surface of melanoma cells. Decameric peptides (26-35) are being investigated as cancer vaccines.

MLANA
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 2GT9, 2GTW, 2GTZ, 2GUO, 3HG1, 3L6F, 3MRO, 3MRP, 3MRQ, 3QDM, 3QEQ, 3QFD, 4EUP, 4JFF, 4L3E, 4QOK, 4WJ5, 5E9D
Identifiers
Aliases	MLANA, MART-1, MART1, melan-A
External IDs	OMIM: 605513; MGI: 108454; HomoloGene: 4026; GeneCards: MLANA; OMA:MLANA - orthologs
Gene location (Human) Chr. Chromosome 9 (human)[1] Band 9p24.1 Start 5,890,889 bp[1] End 5,910,606 bp[1]
Gene location (Mouse) Chr. Chromosome 19 (mouse)[2] Band 19 C1|19 24.28 cM Start 29,675,224 bp[2] End 29,686,034 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in skin of thigh retinal pigment epithelium skin of abdomen testicle skin of arm gonad vulva skin of hip human penis monocyte Top expressed in iris ciliary body hair follicle stria vascularis skin of abdomen retinal pigment epithelium embryo epithelium of lens embryo skin of back More reference expression data BioGPS More reference expression data
Orthologs Species Human Mouse Entrez 2315 77836 Ensembl ENSG00000120215 ENSMUSG00000024806 UniProt Q16655 Q2TA50 RefSeq (mRNA) NM_005511 NM_029993 RefSeq (protein) NP_005502 NP_084269 Location (UCSC) Chr 9: 5.89 – 5.91 Mb Chr 19: 29.68 – 29.69 Mb PubMed search [3] [4]
Wikidata
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Immunohistochemistry stain for Melan-A in a poorly differentiated metastatic melanoma to a lymph node, helping in its diagnosis

Discovery and nomenclature

The names MART-1 and melan-A were coined by two groups of researchers who independently sequenced the gene for this antigen in 1994. Both names are currently in common use. Kawakami et al. at the National Cancer Institute coined the term MART-1, which stands for "melanoma antigen recognized by T-cells".^[6] Coulie et al. of Belgium called the gene melan-A, presumably an abbreviation for "melanocyte antigen".^[7]

Clinical significance

MART-1/melan-A is a protein antigen that is found on the surface of melanocytes. Antibodies against the antigen are used in the medical specialty of anatomic pathology in order to recognize cells of melanocytic differentiation, useful for the diagnosis of a melanoma. The same name is also used to refer to the gene which codes for the antigen.

The MART-1/melan-A antigen is specific for the melanocyte lineage, found in normal skin, the retina, and melanocytes, but not in other normal tissues. It is thus useful as a marker for melanocytic tumors (melanomas) with the caveat that it is normally found in benign nevi as well.

In many immunological studies melan-A peptides serve as a positive control for T-cell priming experiments. This is due to the fact that its high precursor frequency of about 1/1000 among cytotoxic T-cells makes it easy for antigen presenting cells to evoke peptide-specific responses.^[8]

Structure

MART-1/melan-A is a putative 13 kDa transmembrane protein consisting of 118 amino acids. It has a single transmembrane domain.

Regulation

Its expression is regulated by the microphthalmia-associated transcription factor.^[9][10]