The cardiac form of the tissue-specific SmN protein is identical to the brain and embryonic forms of the protein.
The SmN protein is a component of small nuclear ribonucleoprotein particles and closely related to the ubiquitously expressed SmB and B' splicing proteins. However, SmN is only expressed in a limited range of tissues and cell types such as brain, heart and early embryonic cells. The isolation of cDNA clones derived from the mRNA encoding SmN in different cell types has indicated that the brain and embryonic forms of the protein are identical and are encoded by a distinct gene to that encoding SmB and B'. It has been suggested however, that the cardiac form of SmN is encoded by a distinct mRNA which is derived from a different gene from that encoding the brain and embryonic forms of SmN. By using the polymerase chain reaction as well as cDNA cloning we have shown that this is not the case and that the cardiac, brain and embryonic forms of the protein are identical and are translated from the same mRNA encoded by a single gene. The significance of this finding is discussed in terms of the complex expression pattern of this gene and the possible functional role of SmN.
Department of Biochemistry, University College and Middlesex School of Medicine, London, UK.
D
D
Gerrelli
K
K
Grimaldi
D
D
Horn
U
U
Mahadeva
N
N
Sharpe
D S
DS
Latchman
D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000032:analysis* / Q000096:biosynthesis; D001483:Base Sequence; D001923:Brain Chemistry / Q000502:physiology*; D003001:Cloning, Molecular; D004247:DNA; D004622:Embryo, Mammalian / Q000737:chemistry*; D005326:Fetal Proteins / Q000032:analysis*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry*; D009928:Organ Specificity / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D017411:Ribonucleoproteins, Small Nuclear / Q000032:analysis* / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D055517:snRNP Core Proteins
D001324:Autoantigens; D005326:Fetal Proteins; D012333:RNA, Messenger; D017411:Ribonucleoproteins, Small Nuclear; C526407:SNRPB protein, human; C526417:SNRPN protein, human; C526416:Snrpb protein, mouse; D055517:snRNP Core Proteins; D004247:DNA