dra

Dra, or DRA, is a term that can refer to multiple concepts across different fields. It is not tied to a single definition; its meaning depends on context, and it often appears as an acronym or as a proper name.

In biology, DRA most notably refers to the HLA-DRA gene, which encodes the alpha chain of the HLA-DR antigen-presenting molecule. This protein is part of the major histocompatibility complex class II and is expressed mainly on antigen-presenting cells such as dendritic cells, macrophages, and B cells. The HLA-DR complex presents extracellular peptide antigens to CD4+ T helper cells, playing a central role in initiating immune responses. Genetic variation at the HLA-DRA locus has been studied in transplantation compatibility and in autoimmune disease risk, though the overall system involves many interacting genes.

Beyond this gene symbol, DRA is used as an acronym or name in other domains. It can appear in corporate or organizational titles, or as a component of place names or personal names in various languages. The meaning of DRA in any given source therefore depends on domain-specific context.

Because "Dra" is ambiguous, readers should determine the intended sense from the surrounding text or documentation. If a specific field or usage is intended, that context will guide the correct interpretation.