Figure 4

Multidomain architectures of interkingdom fusion proteins and their homologs (examples). (a) The three-domain uridine kinase; (b) the sialic acid synthase homologous domain fused to hydroxymethylpyrimidine phosphate kinase. Domain name abbreviations: TTRS, threonyl-tRNA synthetase; UDK, uridine kinase; TGS and H3H, amino-terminal domains of TTRS; HMP-PK, hydroxymethylpyrimidine phosphate kinase; SISH, sialic acid synthase homologous domain; HTH, helix-turn-helix DNA-binding domain. Different shades represent distinct sequence families of each domain. Species name abbreviations: Tp, Treponema pallidum; Tm, Thermotoga maritima; Mth, Methanobacterium thermoautotrophicum; Mj, Methanococcus jannaschii; Ap, Aeropyrum pernix; Ph, Pyrococcus horikoshii; Pa, Pyrococcus abyssii.