Rat Phospholipid-hydroperoxide Glutathione Peroxidase

Abstract

Phospholipid-hydroperoxide glutathione peroxidase (PhGPx) is a selenoenzyme that reduces hydroperoxides of phospholipid, cholesterol, and cholesteryl ester. Previous studies suggested that both the mitochondrial and nonmitochondrial forms of PhGPx are ϳ170 amino acids long. In this study, we isolated a full-length cDNA clone encoding rat testis PhGPx. Based on sequence analysis, the cDNA encodes a protein of 197 amino acids, with translation initiating at AUG 61 . The additional 27 amino acids at the N terminus contain the features of a mitochondrial targeting sequence. In vitro translation of the full-length PhGPx mRNA initiated predominantly at AUG 61

Distinct Promoters Determine Alternative Transcription of gpx-4 into Phospholipid-Hydroperoxide Glutathione Peroxidase Variants

“…Otherwise, the total genomic sequence now established, Ϫ1497 to ϩ 2714 (not shown; GenBank TM accession no. AJ537598), is remarkably congruent with published cDNAs (25) and partial genomic sequences (24). Just the insertion of a gctccgg motif upstream of the translation start of mPHGPx, if compared with the mRNA reported by Puspha-Rekka et al (25), deserves to be mentioned.…”

“…The PHGPx gene is composed of eight exons that, depending on species, are spread over 3 to 4 kb of DNA. It is transcribed into mRNAs of different lengths (25)(26)(27), which lead to three different isoforms differing in their N-terminal extensions: a cytosolic one (cPHGPx), a mitochondrial one (mPHGPx), and nPHGPx. cPHGPx and mPHGPx are derived from the same exon (designated 1A; see Fig.…”

Human BAG-1/RAP46 protein is generated as four isoforms by alternative translation initiation and overexpressed in cancer cells

“…Since neither the upstream CUG nor the ®rst AUG of hBAG-1 mRNA is in the optimal Kozak sequence, translation may start from the ®rst, second or third AUG. By optimization of CTG-context and each of the three ATGs-context into Kozak sequence, we provided both in vitro and in vivo evidence that alternative initiation of hBAG-1 is caused by the leaky scanning mechanism. Although not common, use of alternative translation initiation sites occurs in other genes such as c-myc (Spotts et al, 1997), cot (Aoki et al, 1993) and glutathione peroxidase (Pushpa-Rekha et al, 1995). In addition, proteins translated by alternative initiation of translation from start codon AUGs were previously shown to have di erent transforming activity (Aoki et al, 1993) or transactivation function (Spotts et al, 1997).…”

Molecular Cloning and Characterization of a cDNA Encoding Putative Phospholipid Hydroperoxide Glutathione Peroxidase from Spinach

“…respectively. Among mammalian proteins, PHGPXs from human testis,8) pig heart,9) pig blastocyst, 1 0) rat brain,ll) and rat testis 12 ) showed 51,50,50,50, and 50% similarity with the spinach protein, respectively. The number of conserved amino acid residues among three plant proteins and that among the spinach protein and five mammalian PHGPXs are 119 and 84, respectively.…”

“…Conserved amino acid residues are boxed, and the Cys corresponding to the SeCys in mammalian PHGPXs is indicated by an arrowhead. The SeCys is indicated by X. Amino acid sequences of mammalian PHGPXs are mature form suggested by Pushpa-Rekha et al 12 ) SP, spinach putative PHGPX; TB, tobacco putative PHGPX 6 1; AR, Arabic/op.I'is putative PHGPX; CT, citrus putative PHGPX 7 1; HT. human testis PHGPx 8 l; PH.…”