A polypeptide that is one of the class I major histocompatibility markers on cell surfaces; it is grouped into chains of low molecular weight called light chains. The ß2-m chain may be affected by the nef gene in HIV, preventing CD8+ T lymphocytes from recognizing the virus.See: acquired immunodeficiency syndrome; major histocompatibility complex
any globulin, or any fragment of a globulin, of low molecular weight.
a polypeptide found free in serum and which also combines with the α (heavy) chain to form class I major histocompatibility heterodimer. See also major histocompatibility complex.