Histone H2AX phosphorylation and DNA damage

There are several variants of H2A, including H2A.1, H2A.2, H2A.Z, and H2A.X. Each of these H2A variants may be phosphorylated. Mice lacking H2AX are radiation sensitive, growth retarded, immune deficient, and have frequent 

Yeast H2A has the PI-3 kinase motif found in mammalian H2AX. This motif is important for yeast to repair DSBs and in non-homologous end joining. The yeast enzyme catalyzing phosphorylation of yeast H2AX at Ser-129 (homologous to serine 139 of mammalian H2AX) is Mecl [100] (Fig. 8). 

Drosophila melanogaster H2Av is a member of the H2A.Z family. However, Drosophila H2Av is phosphorylated like mammalian H2A.X in response to doublestrand breaks resulting from y-irradiation. The phosphorylation occurs at Ser-137 located in the C-terminus of H2Av [108] (Fig. 8). 

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