Opiorphin prepropeptide (OPRPN)

Opiorphin prepropeptide (OPRPN) encodes a member of the proline-rich protein family and gives rise to the pentapeptide opiorphin, an endogenous inhibitor of the enkephalin-inactivating enzymes neprilysin and aminopeptidase N[1][2][3][7][8][9]. This results in reduced degradation of opioid peptides such as substance P and met-enkephalin, leading to analgesic effects by facilitating enkephalin-mediated, opioid receptor-dependent pathways[1][2][3][5][9]. OPRPN is expressed mainly in tissues such as the salivary gland[6]. It has been associated with functions in pain suppression, erectile physiology, and protection of eye surfaces[1][4][8]. Currently, OPRPN/opiorphin is not a defined therapeutic target per se, but is of interest for development of analgesics and modulators of opioid signaling.

Other names

Basic proline-rich lacrimal proteinPROL1PRL1BPLPProline-rich protein 1opiorphin

Not a direct target for marketed drugs; mechanism of biological action is endogenous inhibition of neprilysin and aminopeptidase N, thereby preserving endogenous opioid peptides (met-enkephalin)