The second kappa B element, kappa B2, of the HLA-A class I regulatory complex is an essential part of the promoter.
The MHC class I regulatory complex (CRC) contains the well characterized palindromic kappa B element, kappa B1, to which a number of nuclear factors are known to bind. This cis element plays an important role in controlling the transcription of MHC class I genes. In addition, the CRC contains a second kappa B element, kappa B2, which is located in tandem with the kappa B1 site, 5 bp upstream. In this study, from reporter gene transfection experiments, we present evidence that this kappa B2 site is as important as kappa B1 in regulating HLA-A locus transcription. Mutations introduced into either kappa B site reduced promoter activity to approximately the level obtained when the entire CRC was deleted. Electrophoretic mobility shift and supershift assays showed that the kappa B2-binding complex (BIII) contained a p65-like subunit, but apparently not the p50 subunit of NF-kappa B. Complex BIII also bound to the kappa B1 site, but the kappa B2 sequence was poorly recognized by the kappa B1-binding complex, BI, probably KBF1, the p50 homodimer. These results demonstrate that both kappa B sites are essential components of the promoter and suggest that they may function together to control MHC class I gene transcription.
Mansky
P
P
Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
Brown
W M
WM
Park
J H
JH
Choi
J W
JW
Yang
S Y
SY
D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism; D004586:Electrophoresis / Q000379:methods; D015789:HLA-A2 Antigen / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics* / Q000502:physiology; D011485:Protein Binding / Q000502:physiology; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic / Q000235:genetics; D014162:Transfection
D004268:DNA-Binding Proteins; D015789:HLA-A2 Antigen