Elongation Factor 2

Elongation Factor 2 (EF2), or Ca2+/calmodulin-dependent protein kinase III, is a conserved gene that encodes for the calcium and calmodulin-dependent, GTP-binding Elongation Factor 2 kinase. EF2 is not a part of the main Ser-Thr-Tyr protein kinase family (Ryazanov et al. 1997) and is a single copy gene in insects. EF2 is a cytoplasmic protein that functions in moving the ribosome down the mRNA during translation (Ryazanov et al. 1997). In eukaryotes, EF2 provides the ability to regulate mRNA translation through its numerous phosphorylation sites. When phosphorylated, EF2 is incapable of binding ribosomes, rendering the protein inactive (Browne and Proud 2004).

EF2 has been used in phylogenetic studies of fungi (Kullnig-Gradinger et al. 2002) and arthropods (Pietrantonio et al. 2002; Regier & Shultz 2001). EF2 was able to recover some clades in arthropods with strong bootstrap support and was considered by Regier & Shultz (2001) to be a promising gene equal to EF-1alpha and PolII for higher-level arthropod studies.

We were able to identify the EF2 gene in Apis using the recently published honey bee genome. This gene is highly conserved when compared with other insects sequences (generated by Regier and Schultz 2001). However, in bees there is a relatively large number of short introns (9 in the region we analyzed in Apis) that may make it difficult to amplify a single large fragment of exon. EF2 has similar rates of nonsynonymous substitution and pairwise differences as EF-1alpha, and contains approximately eight indel regions which differ among taxa, and which can be used as characters for phylogenetic analysis (Regier and Shultz 2001).