The T1 parvovirus Minute Virus of Mice (MVM) was used to study the roles that phosphorylation and N-terminal domains (Nt) configuration of capsid subunits may play in icosahedral nuclear viruses assembly. In synchronous MVM infection, capsid subunits newly assembled as two types of cytoplasmic trimeric intermediates (3VP2, and 1VP1:2VP2) harbored a VP1 phosphorylation level fivefold higher than that of VP2, and hidden Nt. Upon nuclear translocation at S phase, VP1-Nt became exposed in the heterotrimer and subsequent subviral assembly intermediates. Empty capsid subunits showed a phosphorylation level restored to VP1:VP2 stoichiometry, and the Nt concealed in their interior. However ssDNA-filled virus maturing at S/G2 lacked VP1 phosphorylation and one major VP2 phosphopeptide, and exposed VP2-Nt. Endosomal VP2-Nt cleavage resulted in VP3 subunits devoid of any phospholabel, implying that incoming viral particles specifically harbor a low phosphorylation status. Phosphorylation provides a mechanistic coupling of parvovirus nuclear assembly to the cell cycle.

T1细小病毒小鼠微小病毒（MVM）用于研究衣壳亚基的磷酸化和N末端域（Nt）构型可能在二十面体核病毒装配中发挥的作用。在同步MVM感染中，衣壳亚基新组装为两种类型的细胞质三聚体中间体（3VP2和1VP1：2VP2），其VP1磷酸化水平比VP2高五倍，并且隐藏Nt。在S期核易位后，VP1-Nt暴露于异三聚体和随后的亚病毒组装中间体中。空的衣壳亚单位显示磷酸化水平恢复到VP1：VP2化学计量，并且Nt隐藏在其内部。然而，在S / G2上成熟的ssDNA填充病毒缺乏VP1磷酸化和一个主要的VP2磷酸肽，并且暴露了VP2-Nt。内体VP2-Nt切割导致VP3亚基没有任何磷酸标记，这意味着传入的病毒颗粒特别具有低磷酸化状态。磷酸化提供细小病毒核装配与细胞周期的机制耦合。