[5][6][7][8] Its 148-amino acid preproprotein, following cleavage of a signal peptide, is further processed to produce either the 27-amino acid gastrin-releasing peptide or the 10-amino acid neuromedin C.[9] These smaller peptides regulate numerous functions of the gastrointestinal and central nervous systems, including release of gastrointestinal hormones, smooth muscle cell contraction, and epithelial cell proliferation.

This is the reason for the observed fact that atropine does not block the vagal effect on gastrin release.

PreproGRP (the unprocessed form of GRP) is encoded in three exons separated by two introns.

[8] Alternative splicing results in multiple transcript variants encoding different isoforms.

[10] Gastrin-releasing peptide and neuromedin C, it is postulated, play a role in human cancers of the lung, colon, stomach, pancreas, breast, and prostate.