Table 2. Human-mouse evolutionary divergence in the protein coding and untranslated regions of domains of human PK and non-PK genes.

K values	Non- PK genes	PK genes	PK expression level		PK expression breadth
					Ubiqui-tous	Nervous tissue		Testis
			High	Low		Up-reg	Down-reg	Up-reg	Down-reg
5′-spacer
K5′	0.346 (0.002)	0.339 (0.013)	0.322 (0.024)	0.356 (0.034)	0.298 (0.026)	0.288 (0.041)	0.396 (0.039)	0.325 (0.047)	0.340 (0.035)
Protein coding regions
Ke	0.171 (0.001)	0.159 (0.003)	0.145 (0.006)	0.186 (0.009)	0.135 (0.006)	0.149 (0.008)	0.177 (0.010)	0.189 (0.013)	0.144 (0.011)
Ka	0.073 (0.001)	0.050 (0.002)	0.042 (0.005)	0.060 (0.005)	0.029 (0.003)	0.031 (0.012)	0.057 (0.008)	0.095 (0.012)	0.046 (0.009)
Ks	0.558 (0.002)	0.548 (0.007)	0.540 (0.017)	0.560 (0.018)	0.530 (0.020)	0.538 (0.026)	0.609 (0.025)	0.510 (0.042)	0.540 (0.017)
Ka/Ks	0.128	0.089	0.080	0.110	0.050	0.090	0.090	0.190	0.080
3′UTR
K3′	0.379 (0.002)	0.376 (0.012)	0.371 (0.038)	0.431 (0.018)	0.322 (0.022)	0.357 (0.028)	0.411 (0.023)	0.447 (0.047)	0.379 (0.021)
Introns
Ki	0.545 (0.001)	0.564 (0.006)	0.556 (0.013)	0.571 (0.014)	0.579 (0.020)	0.533 (0.013)	0.605 (0.021)	0.571 (0.046)	0.508 (0.016)

Evolutionary divergence in the protein coding regions (K_e), 5′UTRs (K_5′), and 3′UTRs (K_3′) was calculated using Kimura's two parameter model [28]. Rates of synonymous (K_s) and non-synonymous (K_a) divergence were calculated using Yang's model [25]. Gene groups are defined in Figure 2 legend. Data are presented as averages and the standard error of the mean (SEM, shown in the parentheses).