The tetratricopeptide repeat (TPR) motif is a degenerate, 34 amino acid sequence found in many proteins and acts to mediate protein-protein interactions in various pathways. At the sequence level, there can be up to 16 tandem TPR repeats, each of which has a helix-turn-helix shape that stacks on other TPR repeats to achieve ligand binding specificity. EDRF1 (erythroid differentiation-related factor 1), also known as C10orf137 (chromosome 10 open reading frame 137), is a 1,238 amino acid protein containing two TPR repeats. Localizing to nucleus, EDRF1 is involved in transcriptional activation of globin genes by regulating DNA-binding activity of GATA-1 transcription factor. EDRF1 may also play an important role in organ development and histological differentiation. EDRF1 exists as four alternatively spliced isoforms and is encoded by a gene mapping to human chromosome 10q26.13.