Antigen
In immunology, antigens (Ag) are structures (aka substances) specifically bound by antibodies (Ab) or a cell surface version of Ab ~ B cell antigen receptor (BCR). The term antigen originally described a structural molecule that binds specifically to an antibody only in the form of native antigen. It was expanded later to refer to any molecule or a linear molecular fragment after processing the native antigen that can be recognized by T-cell receptor (TCR). BCR and TCR are both highly variable antigen receptors diversified by somatic V(D)J recombination. Both T cells and B cells are cellular components of adaptive immunity. The Ag abbreviation stands for an antibody generator.
Cancer/testis antigen family 45, member a5
Cancer/testis antigen family 45, member A5 is a protein in humans that is encoded by the CT45A5 gene.
This gene represents one of a cluster of six similar genes located on the q arm of chromosome X. The genes in this cluster encode members of the cancer/testis (CT) family of antigens, and are distinct from other CT antigens. These antigens are thought to be novel therapeutic targets for human cancers. Alternative splicing results in multiple transcript variants. A related pseudogene has been identified on chromosome 5. [provided by RefSeq, May 2010].