Sequence comparison of Heterosigma akashiwo Tsg1 with putative homologues in rhodophytic plastids and a cyanobacterium. Putative homologues of Tsg1 from Heterosigma akashiwo (accession number EF115378), Emiliania huxleyi (YP_277392), Porphyra purpurea (AAC08278), Gracilaria tenuistipitata var.liui (YP_063707), Cyanidium caldarium (AAF12904), and Synechocystis sp. PCC 6803 (BAA16687) are compared. The HAMP, PAS, HisKA, and HATPase domains are boxed. The H-box which contains the histidine residue, site of phosphorylation, N, G1, F, G2, and G3 sites are bolded.