The M Protein of SARS-CoV: Basic Structural and Immunological Properties

Hu, Yongwu; Wen, Jie; Tang, Lin; Zhang, Haijun; Zhang, Xiaowei; Li, Yan; Wang, Jing; Han, Yujun; Li, Guoqing; Shi, Jianping; Tian, Xiangjun; Jiang, Feng; Zhao, Xiaoqian; Wang, Jun; Liu, Siqi; Zeng, Changqing; Wang, Jian; Yang, Huanming

The C/T transition in TMII leads to Ala/Val changes. Biochemically, both Ala and Val are both non-polar, non-hydrophilic, and have the same pI (pI 5.6). Therefore, no change is predicted concerning the subregional pI (pI 7.90), hydrophilicity (9.10%), (+) charge (4.50%), (-) charge (0) in TMII by the substitution. The only effect would be the change of hydrophobicity (63.6-68.2%), which would also affect the membrane structure by increasing its stability. The fourth substitution is a T/C transition leading to a Ser/Pro change. Both Ser and Pro are neutral and have the same pI (pI 5.6), but Ser is absolutely hydrophilic. The only predicted change is a slight alteration in the subregional hydrophilicity (45.4-44.7%), leaving all the other physical and chemical features unaltered. However, hydrophilicity should be important to this interior region if the internal environment is taken into consideration.