Characterization of the phosphoglucose isomerase gene from crickets: an analysis of phylogeny, amino acid conservation and nucleotide composition.

Although electrophoretic variation in phosphoglucose isomerase (PGI) is often detected in allozyme studies, the Pgi gene has rarely been characterized. Here, I present the cDNA sequence of the Pgi gene from two species of field cricket, Gryllus pennsylvanicus (U65475) and G. veletis (U65476), in which the PGI protein is suspected of being under balancing selection. Phylogenetic analyses support the conclusion that these sequences are truly cricket Pgi. The cricket amino acid sequences are compared to sequences from other taxa to determine conserved residues that may be essential for the function of the protein. Such analysis is necessary as there is no well-resolved structure of the PGI protein. In addition, the compositional bias of cricket Pgi is different from the other animal Pgi genes characterized to date.