Eicosapentapeptide repeats (EPRs): novel repeat proteins specific to flowering plants.

In this report, we describe a novel tandem peptide repeat protein, Eicosapentapeptide repeat (EPR), which occurs notably only in flowering plants. The EPRs are characterized by a 25 amino acid repeat unit, X(2)CX(4)CX(10)CX(2)HGGG, repeated 10 times tandemly. Sequence search revealed that the repeat motif is highly conserved across its occurrence. EPRs are predicted to exist as quasi-globular stable structures owing to highly conserved amino acid positions and potential disulfide bridges. Proteins containing EPRs are predicted to be located in chloroplasts; non-enzymatic and peptide or DNA-binding in molecular function; and they are possibly involved in transcription regulation.