Kinase Family NKF5

This is probably the oddest of ePK families. It is almost entirely restricted to chordates, with SgK307 (TEX14) found in all chordates and in the honey bee, and SgK424 found only in placental mammals. The kinase domain of SgK307 is very divergent, with only about 25% sequence identity in the kinase domain relative to any other kinase. SgK424 is even more divergent, and while clearly a paralog of SgK307, the kinase domain shows only weak similarity (~28% ID) to SgK307 and just marginal similarity in the C lobe to other kinases.

Even odder is that it is dubious whether SgK424 is a real gene. There are very few ESTs in any species, and genomic comparisons show that the ORFs encoded by these ESTs are often interrupted by stops and frameshifts, or lack correct splice sites in other species. Ka/Ks shows some evolutionary constraint between dog, rodents, and primates within parts of the ORF, but it is difficult to know what protein - if any - is made from the gene in any species.