Vancompernolle K, Goethals M, Huet C, Louvard D, Vandekerckhove J
Laboratory of Physiological Chemistry, University of Ghent, Belgium.
EMBO J. 1992 Dec;11(13):4739-46. doi: 10.1002/j.1460-2075.1992.tb05579.x.
The actin binding sites of actobindin and thymosin beta 4, two small polypeptides that inhibit actin polymerization by interacting with monomeric actin, have been localized using peptide mimetics. Both sites are functionally similar and extend over 20 residues and are located in the NH2-terminus of the polypeptides. They can be dissected into two functional entities: a conserved hexapeptide motif (LKHAET or LKKTET), which forms the major contact site through electrostatic interactions with actin, and a non-conserved NH2-terminal segment preceding the motif, which exerts the inhibitory activity on actin polymerization probably by steric hindrance. The introduction of a glutamic acid at the third position in the motif, creating LKEAET or LKETET sequences, which are similar to those found in some F-actin binding proteins, converts the peptide's inhibitory phenotype into an F-actin stimulatory property. These results allow the proposal of a simple model for G- to F-actin modulation.
肌动蛋白结合蛋白和胸腺素β4是两种通过与单体肌动蛋白相互作用来抑制肌动蛋白聚合的小多肽，其肌动蛋白结合位点已通过肽模拟物进行了定位。这两个位点在功能上相似，延伸超过20个残基，且位于多肽的NH2末端。它们可被分解为两个功能实体：一个保守的六肽基序（LKHAET或LKKTET），通过与肌动蛋白的静电相互作用形成主要接触位点；以及该基序之前的一个非保守NH2末端片段，其可能通过空间位阻对肌动蛋白聚合发挥抑制活性。在基序的第三个位置引入谷氨酸，产生LKEAET或LKETET序列，这些序列与一些F-肌动蛋白结合蛋白中的序列相似，从而将该肽的抑制表型转变为F-肌动蛋白刺激特性。这些结果为G-肌动蛋白向F-肌动蛋白的调节提出了一个简单模型。
