Mass spectrometric analysis of rat ovary and testis cytosolic glutathione S-transferases (GSTs): identification of a novel class-alpha GST, rGSTA6*, in rat testis.
Cytosolic glutathione S-transferases (GSTs) from rat ovaries and testis were purified by a combination of GSH and S-hexylglutathione affinity chromatography. The isolated GSTs were subjected to reverse-phase HPLC, electrospray MS and N-terminal peptide sequencing analysis. The major GST isoenzymes expressed in ovaries are subunits A3, A4, M1, M2 and P1. Other isoenzymes detected are subunits A1, M3 and M6*. In rat testis, the major GST isoenzymes expressed are subunits A3, M1, M2, M3, M5* and M6*. Subunits A1, A4 and P1 are expressed in lesser amounts. We could not detect post-translational modifications of any GSTs with known cDNA sequence. The molecular masses of subunits M5* and M6*, two class-Mu GSTs that have not been cloned, were determined to be 25495 and 26538 Da respectively. An N-terminally modified protein from rat testis with molecular mass 25737 Da was isolated from the S-hexylglutathione column. Results from internal peptide sequencing analysis indicate that this is a novel class-Alpha GST that has not been previously reported. We designate this protein rGSTA6*.
Hsieh
C H
CH
Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan, Republic of China.
Tsai
S P
SP
Yeh
H I
HI
Sheu
T C
TC
Tam
M F
MF
D000595:Amino Acid Sequence; D000818:Animals; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005982:Glutathione Transferase / Q000737:chemistry*; D007527:Isoenzymes / Q000737:chemistry; D008297:Male; D008969:Molecular Sequence Data; D010053:Ovary / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012697:Serine Endopeptidases / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013737:Testis / Q000201:enzymology*
D007527:Isoenzymes; D005982:Glutathione Transferase; D012697:Serine Endopeptidases; C036813:lysyl endopeptidase