| Summary: | 碩士 === 國立臺灣大學 === 微生物學研究所 === 104 === Hepatitis B virus (HBV) core protein (HBc) is a 183-amino acid protein, in which the 1-149 a.a. N-terminal domain is sufficient for nucleocapsid assembly and the 149-183 a.a. C-terminal domain (CTD) is critical for viral RNA encapsidation. The HBc-CTD contains several serine residues, including S155, S162, S170, as the major phosphorylation sites. As revealed by site-directed mutagenesis, the phosphorylation of HBc-CTD might regulate HBV RNA encapsidation and DNA synthesis, which however still awaits to be confirmed in wild-type HBV replicon. Identification of the putative cellular kinase(s) that phosphorylates specific serine residues at HBc-CTD will help address this issue. Though several candidate kinases were identified mainly by in vitro kinase assay, but none of them were proven to occur in cells undergoing active viral replication. The putative kinases are thus still remained to be identified.
The current study proposed to identify the kinase for Serine-170 of HBc-CTD by using the C-S170 antibody, which can specifically recognize the HBc with dephosphorylated S170. The HBc expressing cells were treated with a panel of kinase inhibitors and then processed for the Western blotting by probing with C-S170 antibody. The result pointed out Akt as one candidate in regulating HBc-S170 phosphorylayion. The phosphatase reaction helps illustrate that ~30% of HBc protein in cells is affected by the Akt inhibitor treatment. Regarding to that the Akt is activated at the membrane compartment, the fractionation analysis further demonstrated that the core protein at the membrane compartment is the target HBc to be regulated by Akt. In conclusion, the current study identified that Akt might contribute to the phosphorylation of HBc-S170 at the membrane compartment. This phoshsphorylation in regualating the viral replication is worthy to be further investigated.
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