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Figure 18 | BMC Evolutionary Biology

Figure 18

From: Ancient intron insertion sites and palindromic genomic duplication evolutionally shapes an elementally functioning membrane protein family

Figure 18

Two separate phylogenetic trees for the IRK N terminal plus membrane-spanning region and for the IRK C terminal region. This figure illustrates only the upper halves of the trees and the following figure 19 does the lower halves. a, b, c and d, and m, n, o and p indicate the continuation of branches from the upper halves in this figure to the lower halves in the following figure. Two sets of AA sequence alignments are obtained from two sets of AA sequences divided at the 3' terminal of respective M2 regions in a total of 7 (underlined) and 108 IRK AA sequences of tunicates and vertebrates, inferred from the established genome databases, JGI, GenBank, and Ensembl, except Halocynthia data, the same data as in Fig. 5. In this figure the 270 sites used in the tree of Fig. 5 were divided into 123 sites from the membrane and pore regions and into 147 sites from the C-terminal region. This region was defined as from the 3' end of the M2 region to the end. Both trees for these two regions were made by the Mega3 v3.1 program, as described in the legend of Fig. 5, that is, phylogenetic trees being constructed by the Neighbor-joining methods of Mega 3 v3.1 with the Bootstrap test (500 repetition) and with the Gamma distance model of alpha parameter 2.0. The outgroups were two sets of seven bacterial IRK genes similarly divided at the 3' terminal of respective M2 regions. It was concluded that the C-terminal region of the G-protein-activated IRK group (a total 147 AA sites) revealed a rather slower evolutionary rate or lower mutational rate than that of the ATP-regulated IRK group, except for the Kcnj1 subgroup, and the N-terminal and membrane-spanning region (123 AA sites) of the ATP-regulated IRKs revealed slower evolutionary rates than the same region of the G-protein-activated IRK group.

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