The nucleocapsid (N) protein is conserved in all four genera of the coronaviruses, namely alpha, beta, gamma, and delta, and is essential for genome functionality. Bioinformatic analysis of coronaviral N sequences revealed two intrinsically disordered regions (IDRs) at the center of the polypeptide. While both IDR structures were found in alpha, beta, and gamma-coronaviruses, the second IDR was absent in deltacoronaviruses. Two novel coronaviruses, currently placed in the Gammacoronavirus genus, appeared intermediate in this regard, as the second IDR structure could be barely discerned with a low probability of disorder. Interestingly, these two are the only coronaviruses thus far isolated from marine mammals, namely beluga whale and bottlenose dolphin, two highly related species; the N proteins of the viruses were also virtually identical, differing by a single amino acid. These two unique viruses remain phylogenetic oddities, since gammacoronaviruses are generally avian (bird) in nature. Lastly, both IDRs, regardless of the coronavirus genus in which they occurred, were rich in Ser and Arg, in agreement with their disordered structure. It is postulated that the central IDRs make cardinal contributions in the multitasking role of the nucleocapsid protein, likely requiring structural plasticity, perhaps also impinging on coronavirus host tropism and cross-species transmission.

核衣壳（N）蛋白在冠状病毒的所有四个属中均是保守的，即α，β，γ和δ，并且对基因组功能至关重要。冠状病毒N序列的生物信息学分析揭示了在多肽中心的两个固有无序区（IDR）。虽然两个IDR结构都在α，β和γ冠状病毒中发现，但第二个IDR在δ冠状病毒中不存在。两种新的冠状病毒，目前被放置在丙种冠状病毒中属，在这方面似乎是中间的，因为几乎不能以低的混乱可能性辨别第二IDR结构。有趣的是，这两种是迄今为止从海洋哺乳动物中分离出的仅有的冠状病毒，即白鲸和宽吻海豚这两个高度相关的物种。病毒的N个蛋白质实际上也相同，只是一个氨基酸有所不同。这两种独特的病毒仍然是系统发育上的怪胎，因为γ冠状病毒通常是禽类（鸟）。最后，两个IDR都与它们的无序结构一致，而与它们所处的冠状病毒属无关，都富含Ser和Arg。假设中央IDR在核衣壳蛋白的多任务作用中起主要作用，可能需要结构可塑性，