Hydrophobic strip-of-helix algorithm for selection of T cell-presented peptides.
Hydrophobic strip-of-helix algorithm for selection of T cell-presented peptides.
复制标题
用于选择 T 细胞呈递肽的疏水螺旋带算法。
DOI：
10.1016/0161-5890(87)90068-x
复制
发表时间：
1987
影响因子：
3.6
通讯作者：
Humphreys,RE
中科院分区：
文献类型：
--
作者：
Stille,CJ;Thomas,LJ;Reyes,VE;Humphreys,RE
在Ii的两亲性α螺旋（Phe 146 − Val 164）与外源抗原呈递位点结合通过疏水氨基酸残基的II类MHC分子的（desetope）（Phe 146，Leu 150，Leu 153，Met 157，Ile 160，Val 164），它们存在于沿螺旋沿着的轴向条带中，我们开发了一种算法来搜索显示类似的疏水螺旋带的T细胞呈递肽。这些肽可能与II类MHC分子位点结合，该位点与I疏水性螺旋带互补。螺旋带疏水性指数是在位置n、n+ 4、n+ 7、n+ 11、n+ 14和n + 18处，螺旋的3-6个转角的轴向条带中的氨基酸组的平均疏水性（来自Kyte-Doolittle值）。与T细胞反应性良好相关的肽具有：（1）12-19个氨基酸（3-5个环或4-6个α螺旋转角），（2）具有高度疏水残基的条带，（3）相邻的适度亲水条带，和（4）无脯氨酸。假定的抗原螺旋的其余部分的亲水性程度高于阈值不计入该指数。也就是说，两亲性的大小不被认为是T细胞呈递肽的主要选择因素。这种简单的算法来定量推定的两亲性α螺旋中的螺旋疏水性条带，允许否则通常为亲水性残基，预测了7种充分研究的蛋白质中12种T细胞呈递肽中的10种。分析了该算法的推导和应用。
In extension of the hypothesis that an amphipathic alpha helix of Ii(Phe146−Val164) bound to the foreign antigen-presenting site (desetope) of class II MHC molecules through hydrophobic amino acid residues (Phe146, Leu150, Leu153, Met157, Ile160, Val164) which were present in an axial strip along one side of the Iihelix, we developed an algorithm to search for T cell-presented peptides showing a similar hydrophobic strip-of-helix. Such peptides might bind to the class II MHC molecule site which was complementary to the Iihydrophobic strip-of-helix. The strip-of-helix hydrophobicity index was the mean hydrophobicity (from Kyte-Doolittle values) of sets of amino acids in axial strips down sides of helices for 3–6 turns, at positions,n,n+ 4,n+ 7,n+ 11,n+ 14, andn+ 18. Peptides correlating well with T cell responsiveness had: (1) 12–19 amino acids (3–5 cycles or 4–6 turns of an alpha helix), (2) a strip with highly hydrophobic residues, (3) adjacent, moderately hydrophilic strips, and (4) no prolines. The degree of hydrophilicity of the remainder of a putative antigenic helix above a threshold value did not count in this index. That is, the magnitude of amphipathicity was not judged to be the principal selecting factor for T cell-presented peptides. This simple algorithm to quantitate strip-of-helix hydrophobicity in a putative amphipathic alpha helix, allowing otherwise generally hydrophilic residues, predicted 10 of 12 T cell-presented peptides in seven well-studied proteins. The derivation and application of this algorithm were analyzed.