RNA Ligase Molecular Cell Zachary A Wood, Robert S Sabatini, Stephen L Hajduk  Molecular Cell  Volume 13, Issue 4, Pages 455-456 (February 2004) DOI: 10.1016/S1097-2765(04)00089-9

Figure 1 Functional Domains of T4 RNA Ligase 2 (A) A schematic of T4 Rnl2 with the N-terminal (NTD) and C-terminal domains (CTD) identified as blue and red bars, respectively. The conserved nucleotidyl transferase domains I, III, IIIa, IV, and V are indicated. (B) Mechanism of Rnl2, with the minimal construct of Rnl2 required for a particular step. Step 1: the adenylation of a lysine in Rnl2 with AMP (Ap) and the release of adenylated (AppRNA) by full-length Rnl2. Step 3: The ligation of the AppRNA and release of AMP requires only the NTD of Rnl2. (C) Proposed hydrolysis of App-RNA and of adenylated NTD. Step 2a: The reverse reaction of RNA adenylylation by NTD. Step 2b: Possible hydrolysis of the phosphoanhydride bond of App-RNA by the NTD. Step 1a: Predicted hydrolysis of the phosphoamide bond in NTD of Rnl2. Molecular Cell 2004 13, 455-456DOI: (10.1016/S1097-2765(04)00089-9)