Sequence comparison of the tandem repeat regions of OGFr, MUC1, and the alternative reading frame of the OGFr tandem repeat region (OGFr-ARF). The sequences are derived from the central, most frequently occurring repeat. Minor variations in the sequence of both MUC1 and OGFr repeats occur in the flanking repeats. OGFr shares 20% identity with MUC1, and has positional conservation of 4 of 5 prolines with MUC1. OGFr-ARF shares 30% identity with MUC1. The projection showing the MUC1 amino acids involved in the poly-proline beta-turn "loop" secondary structure are from Fontenot et al. (13). The secondary structures of OGFr and OGFr-ARF remain to be determined experimentally.