Figure 4.

Alignment of the TK sequence of VKR proteins using the CLUSTALW algorithm. Numbers I to XI correspond to the eleven subdomains conserved in protein kinase domains. Essential motifs for protein kinase activity are indicated in red. The motif G₈xGxxGxV₁₅ is required for binding of ATP and V₃₂AxK (16×)E₅₂ for its stabilization. The motif H₁₄₇RD(L/V/I)xxRNxL₁₅₆ is implicated in phosphotransfer and the triplet D₁₉₄FG₁₉₆ is the Mg²⁺ binding site. The two residues Y₂₁₁ and Y₂₁₂ constitute the autophosphorylation site and the motif M₂₆₂(A/S)PE₂₆₅ is required for stabilization of the active kinase core.