Levitide, a neurohormone-like peptide from the skin of Xenopus laevis. Peptide and peptide precursor cDNA sequences

A novel peptide, levitide, less than Glu-Gly-Met-Ile-Gly-Thr-Leu-Thr-Ser-Lys-Arg-Ile-Lys-Gln-NH2 has been isolated from skin secretions of the South African frog Xenopus laevis and sequenced by fast atom bombardment mass spectrometry. Synthetic oligonucleotides were used as probes to screen a X. laevis skin cDNA library for species coding for preprolevitide. Two such clones were detected and their sequences are reported here. Preprolevitide is 88 residues long, exhibits a putative signal sequence at the amino terminus, and contains the levitide peptide at the carboxyl terminus. The levitide precursor shows a striking nucleotide and amino acid (86%) sequence homology with the precursor of xenopsin, a biologically active octapeptide from Xenopus skin, and also encodes a 25-residue amphipathic peptide that is released by processing at a single arginine residue.