Sequence of full length cDNA for human S-adenosylhomocysteine hydrolase.

Two cDNA clones for human S-adenosylhomocysteine hydrolase isolated from a placental cDNA library were sequenced. Each contained a sequence of 1299 nucleotides encoding a 432 amino-acid protein of MW 47,660. Clone 16-1 contained 47 nucleotides 5' of the coding region, and a 780 nucleotide 3' flanking region terminating in a poly A tail. In addition, a 101 nucleotide unprocessed intron interrupted the coding sequence at nucleotide 854 (second base of codon 285). Clone 20-1 contained 43 nucleotides 5' and 742 nucleotides 3' flanking the uninterrupted coding region. Besides the intron, the clones differed in one position of the coding sequence and at two positions of the 3' non-coding region. The cDNAs for human and rat S-adenosylhomocysteine hydrolase were identical at 91.5% of positions in the coding sequence and showed 70% homology in the 3' non-coding regions. Human and rat S-adenosyl-homocysteine hydrolases are identical at 97% of amino-acid residues, and the Dictyostelium and human enzymes at 75%.