The closely related small nuclear ribonucleoprotein polypeptides N and B/B' are distinguishable by antibodies as well as by differences in their mRNAs and gene structures.
The small nuclear ribonucleoprotein-associated polypeptides N, B and B' comprise a group of highly homologous, Sm epitope bearing proteins. However, N differs from B and B' in several ways. First, despite the extensive homology between their amino acid sequences, the antigenicity of the proteins N and B, as recognized by the monoclonal anti-Sm antibody, Y-12, is different. Second, whereas three distinct mRNA species encode human B, B', and N, only B appears to be ubiquitously expressed. Third, rodents do not contain mRNA that encodes B'. Fourth, in both humans and rats, mRNAs that encode B/B' (humans) or B (rodents) and N are transcribed from different genes. Fifth, N and B/B' specific probes reveal different size DNA fragments after human genomic DNA is amplified by a polymerase chain reaction based on oligonucleotides that simultaneously recognize cDNAs encoding N, B, and B'.
Schmauss
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Howard Hughes Medical Institute Research Laboratories, Yale University School of Medicine, New Haven, Connecticut 06510.
Lerner
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MR
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001483:Base Sequence; D015139:Blotting, Southern; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D004247:DNA / Q000235:genetics; D000939:Epitopes / Q000032:analysis / Q000235:genetics; D015723:Gene Library; D005796:Genes; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D012261:Ribonucleoproteins / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D017411:Ribonucleoproteins, Small Nuclear; D012689:Sequence Homology, Nucleic Acid; D013698:Templates, Genetic; D014158:Transcription, Genetic
D000906:Antibodies; D000939:Epitopes; D046911:Macromolecular Substances; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D004247:DNA