Homology of proteasome subunits to a major histocompatibility complex-linked LMP gene.
The class II region of the major histocompatibility complex (MHC) contains genes encoding at least two subunits of a large, intracellular protein complex (the low molecular mass polypeptide, or LMP, complex). This complex is biochemically similar to the proteasome, an abundant and well conserved protein complex having multiple proteolytic activities. Here we report the isolation of a complementary DNA corresponding to one of the subunits of the LMP complex, LMP-2. The protein predicted from this cDNA sequence closely matches the amino-terminal peptide sequence of a rat proteasome subunit, confirming that the proteasome and the LMP complex share polypeptide subunits. The LMP-2 gene is tightly linked to HAM1, a gene thought to be required for translocating peptide fragments of endogenous antigens into the endoplasmic reticulum for association with MHC class I molecules. These observations suggest that the LMP complex may be responsible for generating peptides from cytoplasmic antigen during antigen processing.
Department of Microbiology & Immunology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0678.
C K
CK
Martinez
J J
JJ
Monaco
D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000276:immunology / Q000378:metabolism; D001483:Base Sequence; D015139:Blotting, Southern; D003434:Crossing Over, Genetic; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics*; D004247:DNA / Q000235:genetics; D005802:Genes, MHC Class II / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics*; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D012150:Polymorphism, Restriction Fragment Length; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000235:genetics*; D051381:Rats; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
D000941:Antigens; D009097:Multienzyme Complexes; D010446:Peptide Fragments; D011506:Proteins; C071313:LMP-2 protein; D004247:DNA; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex