Protein L-Isoaspartate-O-Methyltransferase Domain Containing Protein 2 (PCMTD2)

Comparison of the Cullin binding properties of PCMTD2 mutants M5, M6, M7, and M8, all of which bound Elongin C, suggested that the conserved hydrophobic residue, Val, at the N terminus of the PCMTD2 Cul5-box is important for Cul5 binding, whereas the conserved (Y/F) (L/I) residues at the C terminus are much less important.

PCMTD2 mutant M7, in which the N-terminal Val remained unchanged but the four C-terminal residues of the Cul5-box were replaced by the four C-terminal residues of the KLHDC2 Cul2-box, bound Cul5 similarly to wild type PCMTD2. In contrast, PCMTD2 mutants M5, M6, and M8, in which various combinations of these residues plus the N-terminal Val were mutated to residues found in the Cul2-box of KLHDC2, failed to bind either Cul5 or Cul2.