Nam S, Nakamuta N, Kurohmaru M, Hayashi Y
Department of Veterinary Anatomy, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Japan.
Gene. 1997 Oct 1;198(1-2):245-9. doi: 10.1016/s0378-1119(97)00321-1.
Phospholipid hydroperoxide glutathione peroxidase (PHGPx), a selenoprotein, reduces the hydroperoxides of phospholipid, cholesterol, and cholesteryl ester in biomembranes. In this study, a full-length cDNA clone encoding the PHGPx was isolated from mouse testes using a RACE (rapid amplification of cDNA ends) technique. According to sequence analysis, the cDNA encodes a polypeptide of 197 amino acids (aa) that initiates the translation at ATG(145-147) and contains an inframe TGA selenocysteine codon. It also has selenocysteine insertion sequences in the 3'-UTR that are involved in the insertion of selenocysteine at an opal codon. Moreover, the mouse PHGPx contains the active-site residues Gln108 and Trp163 that interact with selenocysteine, and the N-terminal 27-aa residues that may act as a potential mitochondrial targeting signal. According to the deduced aa analysis, mouse PHGPx shares a high level of aa identity with pig (93.4%), human (92.9%), and rat (98%) PHGPxs. However, the PHGPx mRNA particularly showed a high degree of expression in testis. This suggests that the PHGPx in testis may have more than just an antioxidant function.
磷脂氢过氧化物谷胱甘肽过氧化物酶（PHGPx）是一种硒蛋白，可还原生物膜中磷脂、胆固醇和胆固醇酯的氢过氧化物。在本研究中，使用RACE（cDNA末端快速扩增）技术从小鼠睾丸中分离出编码PHGPx的全长cDNA克隆。根据序列分析，该cDNA编码一个由197个氨基酸（aa）组成的多肽，其在ATG（145-147）处起始翻译，并包含一个框内TGA硒代半胱氨酸密码子。它在3'-UTR中也有硒代半胱氨酸插入序列，这些序列参与在乳白密码子处插入硒代半胱氨酸。此外，小鼠PHGPx包含与硒代半胱氨酸相互作用的活性位点残基Gln108和Trp163，以及可能作为潜在线粒体靶向信号的N端27个氨基酸残基。根据推导的氨基酸分析，小鼠PHGPx与猪（93.4%）、人（92.9%）和大鼠（98%）的PHGPx具有高度的氨基酸同一性。然而，PHGPx mRNA在睾丸中尤其表现出高度表达。这表明睾丸中的PHGPx可能具有不止一种抗氧化功能。
