The murine Sm-D autoantigen: multiple genes, genetic polymorphism, evolutionary conservation and lack of intervening sequences in the coding region.
Antibodies to the Sm nuclear antigen are diagnostic of systemic lupus erythematosus (SLE). MRL/Mp-lpr/lpr mice develop a similar illness, and a proportion also develop anti-Sm. To understand better anti-Sm reactivity in this murine model, we have cloned the murine Sm-D autoantigen. One cDNA clone was 517 bp long with an open reading frame of 357 nucleotides, encoding a 13.3 kDa protein of 119 amino acids. At the nucleotide level, the murine Sm-D cDNA was 89.8% homologous with human Sm-D (94% in the coding region), yet there was identity at the protein level, including a Gly-Arg nine-fold repeated C-terminus motif. Southern blot analysis of PstI-digested genomic DNA from seven mouse strains demonstrated a 7.8 kb band in every strain; in addition, a 2.8 kb band was seen in AKR/J, LG/J and MRL/Mp-lpr/lpr. PCR amplification of genomic DNA showed a single Sm-D gene product of 360 bp, which indicated a lack of intervening sequences. The Sm-D protein is thus highly conserved in evolution, probably owing to its essential role in the physiology of the cell.
Mitsuda
T
T
Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill 27599-7280.
Eisenberg
R A
RA
Cohen
P L
PL
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000235:genetics* / Q000276:immunology; D001483:Base Sequence; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D005796:Genes; D006031:Glycosylation; D006801:Humans; D051379:Mice / Q000235:genetics* / Q000276:immunology; D008817:Mice, Mutant Strains / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D016133:Polymerase Chain Reaction; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000302:isolation & purification; D017411:Ribonucleoproteins, Small Nuclear; D017385:Sequence Homology; D013045:Species Specificity; D055517:snRNP Core Proteins
D001324:Autoantigens; D011994:Recombinant Proteins; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins; D004247:DNA