β-Casomorphin-7 is a milk opioid peptide derived from fragment 60-66 of bovine beta-Casein. It strongly stimulates mucin secretion in the rat jejunum through a nervous pathway and mu-opioid receptor activation. The presence of the Tyr-Pro aromatic sequence makes the peptide selective for the mu receptor while the high contents of proline residues in the sequence makes the peptide resistant to degradation by gastrointestinal enzymes.
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