ISSN:
1432-1211
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract An HLA-DR-positive human B lymphoblastoid cell line, T5-1, and its HLA-DR-negative variant, 6.1.6, were studied to elucidate mechanisms resulting in the nonexpression ofHLA-DR genes in 6.1.6. The cell lines were labeled with35S-methionine in vivo, their proteins immunoprecipitated with a monoclonal HLA-DR-specific antibody, and their two-dimensional gel electrophoresis patterns compared. The T5-1 map showed DR-antigen heavy and light chains, while the 6.1.6 map showed neither chain. When the cells were labeled in the presence of tunicamycin, the two-dimensional map of T5-1 showed nonglycosylated heavy and light chains of DR antigen while that of 6.1.6 did not. RNA was extracted from T5-1 and 6.1.6 cells and translated in rabbit reticulocyte lysates. Two-dimensional gel analysis of the immunoprecipitated proteins from T5-1 revealed spots which were identified as HLA-DR light chain and I invariant on the basis of their precipitation by monoclonal and specific allo- and heteroantibodies, and their molecular weight and pl values. These spots were absent in the 6.1.6 maps, indicating that 6.1.6 has no detectable translatable messenger RNA for HLA-DR light chains. The addition of dog pancreas microsomes to the T5-1 cell-free translation mixture resulted in an increase in the molecular weight of the precursor HLA-DR proteins consistent with glycosylation. Together with earlier cell fusion studies showing thatDR structural genes were intact in 6.1.6, these data suggested that the lesion in 6.1.6 is an alteration in a regulatory element required for transcription ofDR genes or mRNA processing.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00621947
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