A new member of the leucine zipper class of proteins that binds to the HLA DR alpha promoter.
Several mutants derived from transformed human B cell lines are defective in expressing major histocompatibility complex (MHC) class II genes. The failure to express a class II gene in at least one such mutant line has been mapped to the MHC class II X box, a conserved transcriptional element in the promoter region. A complementary DNA encoding a DNA-binding protein (human X box binding protein, hXBP-1) whose target is the human DR alpha X box and the 3' flanking region has now been cloned. This complementary DNA encoded a protein with structural similarities to the c-jun proto-oncogene product, and its target sequence was closely related to the palindromic target sequence of c-jun. Mutation of the hXBP-1 DNA target sequence decreased DR alpha promoter activity in vivo. These studies suggest that the hXBP-1 protein acts as a transcription factor in B cells.
Liou
H C
HC
Department of Cancer Biology, Harvard School of Public Health, Boston, MA 02115.
Boothby
M R
MR
Finn
P W
PW
Davidon
R
R
Nabavi
N
N
Zeleznik-Le
N J
NJ
Ting
J P
JP
Glimcher
L H
LH
D000595:Amino Acid Sequence; D001402:B-Lymphocytes; D001483:Base Sequence; D001665:Binding Sites; D002461:Cell Line, Transformed; D004247:DNA / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D006684:HLA-DR Antigens / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007930:Leucine; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D000090063:Proto-Oncogene Mas; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014162:Transfection
D004268:DNA-Binding Proteins; D006684:HLA-DR Antigens; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D004247:DNA; D007930:Leucine