钙结合蛋白S100A14的结构预测及分析

钙结合蛋白S100A14是S100家族中的新成员,其空间结构与功能尚未阐明。采用服务器PredictProtein对人S100A14进行二级结构预测,利用同源建模法构建S100A14（序列12-102）的空间结构模型,经PROCHECK评估模型的可靠性,并将所构建的单体模型进行分子对接,预测S100A14形成同源二聚体的可能性及模式。结果显示,S100A14与S100A13的蛋白序列一致性最高,其C-端Ca2＋结合区存在多个变异,但Cu2＋和Zn2＋结合位点保守存在;helix I与helix IV较S100A13延伸长,而helix I、helix II和helix IV与S100A13的四个α螺旋一样具有两亲性的结构特征,并且在S100A13中扮演重要角色的W77在S100A14的helix IV（W85）中也保守存在。空间结构上,S100A14与S100A13具极大相似性;分子对接显示S100A14单体间可以通过疏水作用力形成＂X-型螺旋束＂同源二聚体。这些结构特征的分析将为S100A14的功能研究提供重要线索。

Structure prediction and analysis of S100 calcium binding protein A14

S100A14 is a new member of S100 calcium binding protein whose structure and functions are still unclear.In this study,the predict-protein server was used to predict the secondary structure of human S100A14 and a validated model of S100A14（residues 12-102） evaluated by PROCHECK was constructed by homology modeling.Furthermore,molecular docking was performed to explore the possibility of S100A14 homodimer and the forming mode.Protein sequence alignment and structure predictions showed that some mutations in Ca2 ＋-binding domain exist in the C-terminal of S100A14 and most of the Cu2 ＋ /Zn2 ＋ binding sites of S100 protein family were conserved in S100A14.Compared to S100A13,it was indicated that there was a longer extension in the helix I and helix IV of S100A14,and the helix I,helix II and helix IV of S100A14 were all amphiphilic as S100A13.An unique site Trp（S100A13 W77）,reported to play an important role in the novel function of S100A13,also exists in S100A14（W85）.It is also revealed the monomer of S100A14 could form＂X-type four-helix bundle＂homodimer stabilized by hydrophobic interaction as other family members by molecular docking.All these findings provide important clues to functional studies of S100A14.