A 15 kDa proteolipid found in mediatophore preparations from Torpedo electric organ presents high sequence homology with the bovine chromaffin granule protonophore.
Upon SDS PAGE of isolated mediatophore, an acetylcholine-translocating protein, a doublet at 15 kDa was identified. Amino acid sequencing after CNBr cleavage gave a 17 residue-long peptide completely homologous with a sequence of the proton-translocating proteolipid from bovine chromaffin granules. A 51-mer oligodeoxynucleotide corresponding to this sequence was used to screen a library of electric lobe cDNAs constructed in lambda Zap II. A positive recombinant clone was isolated and found to encode the complete sequence of a 15.5 kDa protein highly homologous to the bovine chromaffin or yeast vacuolar ATPase proteolipid. In vitro translation of sense RNA transcripts of the clone indeed yielded a single 15 kDa proteolipid. Northern blot analysis showed that the 1.3 kb mRNA encoding this protein is significantly expressed in nervous tissues but not in electric organ or liver of Torpedo marmorata.
Birman
S
S
Département de Neurochimie, CNRS, Gif-sur-Yvette, France.
Meunier
F M
FM
Lesbats
B
B
Le Caer
J P
JP
Rossier
J
J
Israël
M
M
D000109:Acetylcholine / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002837:Chromaffin Granules / Q000032:analysis*; D002838:Chromaffin System / Q000032:analysis*; D003488:Cyanogen Bromide; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004557:Electric Organ / Q000032:analysis*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000302:isolation & purification; D009693:Nucleic Acid Hybridization; D011510:Proteolipids / Q000235:genetics* / Q000302:isolation & purification; D006180:Proton-Translocating ATPases; D011522:Protons; D012333:RNA, Messenger / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D014101:Torpedo
D046911:Macromolecular Substances; D009419:Nerve Tissue Proteins; D011510:Proteolipids; D011522:Protons; D012333:RNA, Messenger; C050299:mediatophore; D004247:DNA; D006180:Proton-Translocating ATPases; D000109:Acetylcholine; D003488:Cyanogen Bromide