cDNA clones for 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase were isolated from rat liver expression libraries in lambda gt11 by antibody, oligonucleotide, and cDNA screening. One 1860 bp long clone contained a full-length nucleotide sequence coding for the 470 amino acids of each of the two identical subunits of the bifunctional enzyme. This clone also contained untranslated sequences, one 173 bp long upstream from the ATG start codon and one 271 bp long downstream from the TGA stop codon. The clone was terminated by a poly(A) tail of 29 nucleotides.