FIG. 3.

Coimmunoprecipitation of U21, but not U20, with class I molecules from astrocytoma cells. (A and B) Cells expressing C-terminally HA epitope-tagged U20 (A), U21-HA (B), or retroviral vector alone (LNCX) were labeled for 1 h with [³⁵S]methionine, lysed, and immunoprecipitated with either W6/32 or an anti-HA Ab. The asterisk denotes a probable degradation product of U20 that is smaller than the class I heavy chain. (C) Amino acid sequence of U21. The predicted signal sequence (continuous line) and transmembrane region (dashed line) are underlined. Predicted N-glycosylation sites are circled. (D) Schematic representation of sequence in panel C, with the predicted signal sequence shaded and the transmembrane region hatched.