Primary structure of the nuclear forms of phospholipid hydroperoxide glutathione peroxidase (PHGPx) in rat spermatozoa.
Phospholipid hydroperoxide glutathione peroxidase is a monomeric Se-peroxidase highly expressed in mammalian male germ cells. Its nuclear form, sperm nuclei glutathione peroxidase (snGPx), has been originally identified in maturating spermatozoa as a transcription product containing an alternative exon within the phospholipid hydroperoxide glutathione peroxidase gene. In this paper, we show that this form is inconstantly detectable in rat spermatozoa where a 20.0 and 25.9 kDa major forms are detected instead. These have been conclusively characterized. The N-terminus sequence of the 20.0 kDa form confirmed that the protein is identical to cytosolic form, suggesting diffusion into the nucleus. The 25.9 kDa protein represented a truncated form of the previously described nuclear snGPx, lacking the basic nuclear localization signal. This protein is present in two forms differing from each other by the presence of an N-terminal methionine. The presence of traces of the larger snGPx form suggests that exhaustive proteolytic processing of the precursor produces the 25.9 kDa enzyme, although the alternate use of a downstream ATG, at least in rodents, could not be unequivocally ruled out.
Maiorino
Matilde
M
Department of Biological Chemistry, University of Padova, Viale G. Colombo 3, I-35121 Padova, Italy. matilde.maiorino@unipd.it
Mauri
Pierluigi
P
Roveri
Antonella
A
Benazzi
Louise
L
Toppo
Stefano
S
Bosello
Valentina
V
Ursini
Fulvio
F
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000201:enzymology; D002851:Chromatography, High Pressure Liquid; D005979:Glutathione Peroxidase / Q000737:chemistry*; D008297:Male; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry*; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D051381:Rats; D017208:Rats, Wistar; D021241:Spectrometry, Mass, Electrospray Ionization; D013094:Spermatozoa / Q000201:enzymology*
D009687:Nuclear Proteins; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D005979:Glutathione Peroxidase