Molecular cloning of profilin from Tetrahymena thermophila.

The actin-binding protein profilin was isolated from Tetrahymena thermophila by affinity chromatography, and the peptide sequence was determined for part of the protein. The cDNA sequence was obtained by using the peptide sequence, reverse transcription-PCR and 5' and 3' RACE. The cDNA coded for a profilin of 16680Da, which made it among the largest known profilins, and it had a predicted isoelectric point of 8.27. The deduced amino acid sequence was divergent from other profilins, having more than 26% identity only with profilin from Tetrahymena pyriformis. The sequence contained insertions that are also present in profilins from Tetrahymena pyriformis and Trypanosoma brucei. There appeared to be only a single profilin gene and one transcript from this gene.