Nyström S, Wieslander A
Department of Biochemistry, University of Umeå, Sweden.
Biochim Biophys Acta. 1992 Jun 11;1107(1):39-43. doi: 10.1016/0005-2736(92)90326-h.
Isoprenylation is an important posttranslational modification that affects the activity, subunit interactions and membrane anchoring of different eukaryotic proteins. The small, cell-wall-less prokaryote Acholeplasma laidlawii has more than 20 membrane acyl-proteins enriched in myristoyl and palmitoyl chains. Radioactive mevalonate, a precursor to isoprenoids, was incorporated into several specific membrane proteins of 20 to 45 kDa and two soluble proteins of 23-25 kDa, respectively. No acyl proteins and none of the polar acyl lipids became labelled but these are all labelled by radioactive fatty acids. Mevalonate was incorporated mainly into a minor neutral, non-saponifiable lipid which migrated just above a C30-isoprenoid (squalene) on TLC-plates. The isoprenoid chains could not be released by mild alkaline hydrolysis from most of the isoprenylated proteins, although this procedure releases acyl chains from lipids and all acylated proteins. Isoprenylated proteins were enriched in the detergent phase upon partition with the non-ionic detergent Triton X-114. This behaviour is similar to the acyl proteins of this organism and indicates that the isoprenoid chains give the proteins a hydrophobic character.
异戊二烯化是一种重要的翻译后修饰，它会影响不同真核生物蛋白质的活性、亚基相互作用和膜锚定。无细胞壁的小型原核生物莱氏无胆甾原体有20多种富含肉豆蔻酰基和棕榈酰基链的膜酰基蛋白。放射性甲羟戊酸（一种类异戊二烯的前体）分别掺入了几种20至45 kDa的特定膜蛋白和两种23 - 25 kDa的可溶性蛋白中。没有酰基蛋白和极性酰基脂质被标记，但这些都被放射性脂肪酸标记。甲羟戊酸主要掺入一种次要的中性、不可皂化脂质中，该脂质在薄层层析板上的迁移位置略高于C30类异戊二烯（角鲨烯）。尽管该程序可从脂质和所有酰化蛋白中释放酰基链，但温和碱性水解无法从大多数异戊二烯化蛋白中释放异戊二烯链。在用非离子去污剂吐温X - 114分配时，异戊二烯化蛋白在去污剂相中富集。这种行为与该生物体的酰基蛋白相似，表明异戊二烯链赋予了蛋白质疏水特性。
