Bernabeu C, van de Rijn M, Lerch P G, Terhorst C P
Nature. 1984;308(5960):642-5. doi: 10.1038/308642a0.
Beta 2-microglobulin (beta 2-m) is a highly conserved polypeptide (12,000 molecular weight; 12K) noncovalently associated with the heavy chain (45-48K) of the major histocompatibility complex (MHC) class I antigens. Its synthesis is required for expression of the HLA-A/B and H-2K/D heavy chains at the cell surface; beta 2-m is also associated with the human cell-surface antigens T6 and M241 isolated from thymocytes. However, on the T leukaemic cell line MOLT-4 some of the T6 antigens contain a different 12K subunit, termed beta t (refs 3, 7, 8). Purified human beta 2-m can exchange partially both with human beta 2-m associated with HLA-antigens, and with mouse beta 2-m associated with murine alloantigens. As MOLT-4 cells were grown in the presence of fetal calf serum (FCS) and as serum is known to contain some free beta 2-m, we examined whether beta t was bovine beta 2-m which had replaced endogenous beta 2-m on the surface of the cell. Here we show both that beta 2-m from FCS or human serum (HuS) used in cell culture can exchange with beta 2-m on the cell surface, and that beta t is in fact bovine beta 2-m.
β2-微球蛋白（β2-m）是一种高度保守的多肽（分子量12,000；12K），它与主要组织相容性复合体（MHC）I类抗原的重链（45 - 48K）非共价结合。其合成是HLA - A/B和H - 2K/D重链在细胞表面表达所必需的；β2-m也与人胸腺细胞分离出的细胞表面抗原T6和M241相关。然而，在T白血病细胞系MOLT - 4中，一些T6抗原含有一种不同的12K亚基，称为βt（参考文献3、7、8）。纯化的人β2-m可以与人HLA抗原相关的β2-m以及小鼠同种异体抗原相关的小鼠β2-m部分交换。由于MOLT - 4细胞在胎牛血清（FCS）存在的情况下生长，且已知血清中含有一些游离的β2-m，我们研究了βt是否是取代细胞表面内源性β2-m的牛β2-m。在此我们表明，细胞培养中使用的FCS或人血清（HuS）中的β2-m可以与细胞表面的β2-m交换，并且βt实际上就是牛β2-m。
