Analysis of HLA-DMB mutants and -DMB genomic structure.
The HLA-DM locus encodes class II-like A and B chains and apparently regulates the antigen presentation function of conventional major histocompatibility complex (MHC) class II molecules. Here we describe the HLA-DMB mutations in three presentation defective B lymphoblastoid cells lines (B-LCL), 7.19.6, 10.6.6, and 10.78.6, which express DMB transcripts of abnormal length. Mutant 7.19.6 has a C-->T point mutation that introduces a 5' splice site into exon 3 of DMB. The independently derived mutants, 10.6.6 and 10.78.6, each harbor a G-->A mutation in exon 3 and also lack an identical downstream segment of RNA. Mapping of DMB intron/exon borders, using a genomic clone, revealed that the segment missing in mutants 10.6.6 and 10.78.6 represents the fourth exon of DMB; no mutations were found within exon 4 in either 10.6.6 or 10.78.6, however. In addition, the DMB gene was found to have a six exon genomic structure, typical of MHC class II B genes.
Shaman
J
J
Department of Pediatrics, Children's Hospital of Philadelphia, PA 19104.
von Scheven
E
E
Morris
P
P
Chang
M D
MD
Mellins
E
E
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons / Q000235:genetics; D005802:Genes, MHC Class II / Q000235:genetics*; D006681:HLA-D Antigens / Q000235:genetics*; D000949:Histocompatibility Antigens Class II; D006801:Humans; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
D018076:DNA, Complementary; C416189:H2-M antigens; D006681:HLA-D Antigens; C084245:HLA-DM antigens; D000949:Histocompatibility Antigens Class II; D012333:RNA, Messenger; D012194:RNA-Directed DNA Polymerase