Molecular cloning of a cDNA encoding the human Sm-D autoantigen.
Antibodies to the Sm-D polypeptide antigen are closely associated with the rheumatic disease systemic lupus erythematosus. Sm-D exists in the cell as one of the core proteins of the small nuclear ribonucleoprotein complexes implicated in RNA processing. We have isolated a cDNA clone, D45-2, coding for the Sm-D human nuclear antigen by screening a human B-lymphocyte cDNA library with synthetic oligonucleotide probes. The 1633-base-pair clone contains an open reading frame (ORF) 357 nucleotides long, capable of encoding a 13,282-dalton polypeptide. The Sm-D coding region is initiated at an AUG codon downstream from a sequence with excellent match to the consensus for the eukaryotic ribosome-binding site. The Sm-D ORF is preceded by a 150-nucleotide-long untranslated leader and followed by a 1126-nucleotide-long untranslated region containing four putative poly(A) signals. The predicted amino acid sequence reveals a (Gly-Arg)9 repeated motif at the C terminus, which may constitute one of the Sm-D immunoreactive determinants. Moreover, this C terminus shows interesting features: (i) a good homology to protamines as expected for a nucleic acid binding protein and (ii) a striking similarity to a region in the Epstein-Barr nuclear antigen.
Rokeach
L A
LA
Agouron Institute, La Jolla, CA 92037.
Haselby
J A
JA
Hoch
S O
SO
D000595:Amino Acid Sequence; D000956:Antigens, Viral / Q000235:genetics; D001324:Autoantigens / Q000235:genetics*; D001402:B-Lymphocytes / Q000032:analysis; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D019309:Epstein-Barr Virus Nuclear Antigens; D006801:Humans; D008969:Molecular Sequence Data; D011479:Protamines / Q000235:genetics; D017411:Ribonucleoproteins, Small Nuclear; D012689:Sequence Homology, Nucleic Acid; D055517:snRNP Core Proteins
D000956:Antigens, Viral; D001324:Autoantigens; D019309:Epstein-Barr Virus Nuclear Antigens; D011479:Protamines; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins; D004247:DNA