Post-translational modifications of pro-opiomelanocrtin related hormones in medaka pituitary based on mass spectrometric analyses

► The novel molecular forms of α-melanocyte-stimulating hormone (MSH) and β-MSH in medaka (Oryzias latipes var.) pituitary. ► The acetylation sites in triacetyl-α-MSH were determined as N,O-diacetylation of Ser residue at position 1 and O-acetylation of Ser residue at position 3. ► The Pro residue at position 15 was partially hydroxylated in the β-MSH molecule.