The peptide elongation factor 1 alpha (EF-1 alpha) has been isolated and characterised from a number of species. Recently we and others have reported the existence of an isoform of the ubiquitously expressed EF-1 alpha mRNA in higher eukaryotes, including human cells. This isoform has a tissue specific expression pattern, confining it primarily to muscle, heart, and brain. In the present study we have purified the isoform of EF-1 alpha from rabbit muscle. Using partial amino acid analysis, we can conclude that in rabbit muscle essentially only the isoform of elongation factor 1 alpha, designated EF-1 alpha 2, is translated. Preliminary activity assays show that the isoform has the same functional activities as the normal EF-1 alpha, designated EF-1 alpha 1, in relation to protein synthesis, but may behave differently in the ability to bind nucleotides. Based on the availability of the isoforms of EF-1 alpha purified from a mammalian species, it will be possible to conduct further comparative studies in order to elucidate the different functions of EF-1 alpha 1 and EF-1 alpha 2 proteins. (C) 1998 Academic Press.
