Sowadski J M, Ellis C A
Department of Medicine, University of California at San Diego, La Jolla 92093-0654, USA.
J Bioenerg Biomembr. 1996 Feb;28(1):7-12.
Myristylation often governs the targeting of protein kinases to the plasma membrane. It is now known that a key member of the src family of protein tyrosine kinases, pp60v-src, binds to the lipid bilayer of the plasma membrane via a myristylated amino terminal sequence. The mechanism of this interaction is not known; however, myristic acid (Myristic acid may also be referred to as Myristate) and residues 2 through 14 are also absolutely required (Resh and Ling, 1990). This review presents an analysis of crystal structures of detergent-modified recombinant and myristylated mammalian catalytic subunit of protein kinase A. Crystals of unmyristylated recombinant catalytic subunit of protein kinase A are grown in the presence of Mega 8, a glucamide-type of detergent, and only this detergent binds, which results in a resolution extension (Knighton et al., 1991a). Comparisons of these two structures reveal that the detergent association with the recombinant enzyme binds in exactly the same hydrophobic pocket of the protein occupied by myristic acid in the mammalian protein (Karlsson et al., 1993; Zheng et al., 1993a). Removal of the detergent through soaking results in the local unwinding of the first helix, helix A, and disorder of the canonical recognition sequence of the phosphorylation site, Ser 10 (Zheng et al., 1993b). These results suggest that anchoring the myristic acid inside the protein results in formation of a stable structural template, which includes the myristylated amino terminal sequence important for the recognition by protein kinases. This "inside out" motif might provide a structural paradigm for the recognition of myristylated proteins, including pp60v-src.
肉豆蔻酰化作用常常决定蛋白激酶定位于质膜。现在已知蛋白酪氨酸激酶src家族的一个关键成员，即pp60v-src，通过一个肉豆蔻酰化的氨基末端序列与质膜的脂质双层结合。这种相互作用的机制尚不清楚；然而，肉豆蔻酸（肉豆蔻酸也可称为肉豆蔻酸盐）以及2至14位残基也是绝对必需的（雷什和凌，1990年）。本综述对经去污剂修饰的重组且肉豆蔻酰化的蛋白激酶A的哺乳动物催化亚基的晶体结构进行了分析。蛋白激酶A的未肉豆蔻酰化重组催化亚基的晶体在一种葡糖酰胺型去污剂Mega 8存在的情况下生长，并且只有这种去污剂结合，这导致分辨率提高（奈顿等人，1991年a）。对这两种结构的比较表明，去污剂与重组酶的结合位点恰好与哺乳动物蛋白中被肉豆蔻酸占据的蛋白疏水口袋相同（卡尔松等人，1993年；郑等人，1993年a）。通过浸泡去除去污剂会导致第一个螺旋（螺旋A）局部解旋以及磷酸化位点丝氨酸10的典型识别序列紊乱（郑等人，1993年b）。这些结果表明，将肉豆蔻酸锚定在蛋白内部会导致形成一个稳定的结构模板，其中包括对蛋白激酶识别很重要的肉豆蔻酰化氨基末端序列。这种“由内向外”基序可能为包括pp60v-src在内的肉豆蔻酰化蛋白的识别提供一种结构模式。
