A cDNA library was constructed using poly(A)-rich RNA isolated from skin of the frog Bombina variegata. This library was screened with two oligo-nucleotides complementary to parts of the sequence of bombesin. The nucleotide sequence of one of the cloned cDNAs encoding a bombesin precursor is presented. The predicted polypeptide contains a single copy of the end-product. The bombesin sequence is preceded by a leucine residue suggesting an unusual type of precursor processing.
