May C, Preisig-Müller R, Höhne M, Gnau P, Kindl H
Fachbereich Chemie, Philipps-Universität, Marburg, Germany.
Biochim Biophys Acta. 1998 Aug 28;1393(2-3):267-76. doi: 10.1016/s0005-2760(98)00081-2.
A patatin-like protein is present in the storage tissue of cucumber seedlings during the stage of fat mobilization. The cucumber protein is a homologue of a glycoprotein which in potatoes accounts for most of the total protein content of tubers. Following preparation of a cucumber cDNA library representing the developmental stage of cotyledons of 1 day old germinating seeds we isolated and characterized a clone encoding a patatin-like protein. Antibodies raised against the protein expressed in bacteria were used for immunodetection in subcellular fractions of cucumber seedlings. It was shown that the patatin-like protein was virtually exclusively confined to lipid bodies. The protein expressed in bacteria was characterized in vitro by its esterase activity acting on monoacylglycerols and phospholipids. Detailed analysis using various forms of phosphatidyl choline as substrates demonstrated that the patatin-like protein is a phospholipase A2 acting on palmitoyl, linoleoyl and hydroperoxidized linoleoyl groups equally well. Studying the temporal and tissue-specific expression of patatin-like protein mRNA we showed its appearance exclusively during fat catabolism. As maximal amounts of the protein were found at an early stage of mobilization and confined to lipid bodies, we propose that the patatin-like hydrolase is involved in lipid body mobilization.
在黄瓜幼苗脂肪动员阶段的贮藏组织中存在一种类patatin蛋白。该黄瓜蛋白是一种糖蛋白的同源物，在马铃薯中，这种糖蛋白占块茎总蛋白含量的大部分。在构建了一个代表1日龄发芽种子子叶发育阶段的黄瓜cDNA文库后，我们分离并鉴定了一个编码类patatin蛋白的克隆。用针对细菌中表达的该蛋白制备的抗体对黄瓜幼苗的亚细胞组分进行免疫检测。结果表明，类patatin蛋白几乎只存在于脂质体中。通过体外测定其对单酰甘油和磷脂的酯酶活性对细菌中表达的该蛋白进行了表征。以各种形式的磷脂酰胆碱为底物进行详细分析表明，类patatin蛋白是一种磷脂酶A2，对棕榈酰基、亚油酰基和氢过氧化亚油酰基的作用效果相同。通过研究类patatin蛋白mRNA的时间和组织特异性表达，我们发现它仅在脂肪分解代谢过程中出现。由于在动员早期发现该蛋白的含量最高且仅存在于脂质体中，我们推测类patatin水解酶参与脂质体的动员。
