HLA-A（major histocompatibility complex， class I， A），癌症关联基因，基因ID：3105，HLA-A属于HLA I类重链相似度。这一类分子是由重链和轻链（β-2微球蛋白）组成的异二聚体。重链锚定在膜上。I类分子通过呈现内质网腔中的肽在免疫系统中起着中心作用。几乎在所有细胞中都有表达。重链约45kDa，其基因包含8个外显子。外显子1编码先导肽，外显子2和3编码α1和α2结构域，两者结合肽，外显子4编码α3结构域，外显子5编码跨膜区，外显子6和7编码胞质尾。外显子2和外显子3内的多态性负责每一类1分子的肽结合特异性。这些多态性的分型通常用于骨髓和肾移植。已经描述了100多个HLA-A等位基因。HLA-A belongs to the HLA class I heavy chain paralogues. This class I molecule is a heterodimer consisting of a heavy chain and a light chain (beta-2 microglobulin). The heavy chain is anchored in the membrane. Class I molecules play a central role in the immune system by presenting peptides derived from the endoplasmic reticulum lumen. They are expressed in nearly all cells. The heavy chain is approximately 45 kDa and its gene contains 8 exons. Exon 1 encodes the leader peptide， exons 2 and 3 encode the alpha1 and alpha2 domains， which both bind the peptide， exon 4 encodes the alpha3 domain， exon 5 encodes the transmem。