Immune precipitation of the Xg^a and CD99 antigens from transfected RAG cells and erythrocytes.

(A) Intact nontransfected RAG cells or the clone XG13-h.MIC15 were¹²⁵I-labeled and incubated with NBL-1 or 12E7 antibodies, as noted below the autoradiograph. Solubilized complexes were precipitated, separated on SDS-PAGE, and autoradiographed. (B) Erythrocyte surface proteins from Xg(a+) (female), Xg(a−) (male, CD99-high expressor) or Xg(a−) (female, CD99-low expressor) donors were ¹²⁵I-labeled. Cell membranes were prepared, incubated with NBL-1 (or the anti-Xg^a serum Alo.) or 12E7 antibodies, and solubilized complexes were treated as in A. The size (kd) of the detected bands was determined using rainbow-colored protein molecular weight markers (Amersham).