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

A segment (YFV-S- - L- -R-TSMWSFNPE), located between Codons 94 and 114, is identified as partially overlapping with the interior membrane boundary of TMIII (Codons 76-98), which is the most conserved (consensus 70-100%) motif in the M protein among all coronaviruses. It has been suggested that the region containing this consensus could be related to interaction with the N protein and viral RNA (9). We also have found another segment, PETNILLNVP, with two residues overlapping with the C-terminal part of the motif discussed above (—TSMWSFNPE). The blast results reveal that the amino acid sequence of this motif is identical (nt homology = 24/25, identity = 96%) to a segment in Vomeronasal 1 receptor (V1rf2) of mice (AY065513). V1rf2 is a well-known pheromone receptor on the olfactory bulb in mice. It functions in membrane trafficking involved in the transduction of cellular Ca2+ signals to the existing downstream effectors(10). This discovery indicates that the motif might play a crucial role in infecting epithelial cells in the respiratory tract, suggesting a possible link to a respiratory manifestation in SARS.