FIG 1.

Schematic diagram of HBc and DHBc domains and GST-HCTD and -DCTD fusion constructs. (A) HBc contains an N-terminal domain (NTD) from amino acids 1 to 140 and a C-terminal domain (CTD) that includes a flexible linker region from amino acids 141 to 149 and a phosphor (P) domain from 150 to 183. (B) The WT GST-HCTD fusion protein, HCTD141, contains the CTD from residue 141 to the end of HBc. Alanine (A) or glutamic acid (E) substitutions at the three major phosphorylation sites (S155, S162, and S170) or all seven potential phosphorylation sites (T160, S168, S176, and S178 in addition to the aforementioned three major sites) in the WT GST-HCTD fusion protein were named HCTD141-ATASASS, HCTD141-ETESESS, HCTD141-AAAAAAA, and HCTD141-EEEEEEE, respectively. (C) DHBc contains an NTD from amino acids 1 to 185 and a CTD from 186 to 262, including a flexible linker region from amino acids 186 to 228 and the phosphor (P) domain from 229 to 262. (D) The linker region from amino acids 196 to 228 was fused with GST and named DCTD196–228. (E) The WT GST-DCTD fusion protein, DCTD196, contains the linker region and the phosphor domain, in which six phosphorylation sites (S230, S232, T239, S245, S257, and S259) are localized. All six phosphorylation sites in DCTD196 were substituted for A or aspartic acid (D), and the resultant mutants were named DCTD196-AAAAAA and DCTD196-DDDDDD, respectively.