For instance, an alignment of orthologous sequences of the phosphatase Glc7p, which was found to be a NatB target, shows that the protein is in general very well conserved; however, the N- and C-terminal regions display a much lower degree of conservation, making Glc7p not a NatB substrate in even closely related species.
When the two classes of IESs are considered, incompletely excised IESs share the canonical consensus, whereas the termini of cryptic IESs display a much lower level of conservation (fig. 2; supplementary tables S2A and S2B, Supplementary Material online).
However, the most striking feature of this analysis is that in all non-mammalian organisms considered, the non-nucleolar group displays a much lower degree of conservation than any of the nucleolar association groups, and the gap between the non-nucleolar and nucleolar groups greatly increases with evolutionary distance.
Comparisons of the human Hoxa cluster to those of marsupials and amphibians reveal a much lower level of sequence conservation over similar periods of time, indicating either a faster rate of molecular evolution in the tetrapod and mammalian lineages or a slower rate of evolution in the cartilaginous fish.
Several recent studies comparing high throughput data including expression, protein-protein, protein-DNA, and genetic interactions between close species show conservation at a much lower rate than expected.
As a first result, nearly half (44%%) of all strictly conserved genes (conservation code: 111 or 110) were identified as essential, while less conserved genes (conservation code: 011, 010, or 001) showed a much lower probability of being essential (10%).
Thus, in contrast to other tissues, an adult testis would have no particular requirement for N conservation in its proteins, because proteins are being synthesized at a much lower rate.
Due to the high conservation together with the high gene density of this region, a much larger proportion of conserved elements occur in exons (57%) and a much lower proportion in intragenic regions (13%) than the genomic averages (18% and 41.2% respectively).
