Mammalian protein homologous to VAT-1 of Torpedo californica: isolation from Ehrlich ascites tumor cells, biochemical characterization, and organization of its gene.
Recently, interest has focused on the human gene encoding the putative protein homologous to VAT-1, the major protein of the synaptic vesicles of the electric organ of the Pacific electric ray Torpedo californica, after it has been localized on chromosome locus 17q21 in a region encompassing the breast cancer gene BRCA1. Chromosomal instability in this region is implicated in inherited predisposition for breast and ovarian cancer. Here we describe isolation and biochemical characterization of a mammalian 48 kDa protein homologous to the VAT-1 protein of Torpedo californica. This VAT-1 homolog was isolated from a murine breast cancer cell line (Ehrlich ascites tumor) and identified by sequencing of cleavage peptides. The isolated VAT-1 homolog protein displays an ATPase activity and exists in two isoforms with isoelectric points of 5.7 and 5.8. cDNA was prepared from Ehrlich ascites tumor cells, and the murine VAT-1 homolog sequence was amplified by polymerase chain reaction and partially sequenced. The known part of the murine and the human translated sequences share 97% identity. By Northern blots, the size of the VAT-1 homolog mRNA in both murine and human (T47D) breast cancer cells was determined to be 2.8 kb. Based on the presented data, a modified gene structure of the human VAT-1 homolog with an extended exon 1 is proposed. VAT-1 and the mammalian VAT-1 homolog form a subgroup within the protein superfamily of medium-chain dehydrogenases/reductases.
Hayess
K
K
Max-Delbrück-Centrum für Molekulare Medizin, Berlin-Buch, Germany.
Kraft
R
R
Sachsinger
J
J
Janke
J
J
Beckmann
G
G
Rohde
K
K
Jandrig
B
B
Benndorf
R
R
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005091:Exons; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014101:Torpedo; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism
D018076:DNA, Complementary; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C063277:VAT-1 protein, Torpedo; C544158:VAT1 protein, human; D033921:Vesicular Transport Proteins; D000251:Adenosine Triphosphatases