Characterization of two mRNA species encoding human estradiol 17β-dehydrogenase and assignment of the gene to chromosome 17☆

Abstract Using two 33-mer synthetic oligonucleotides derived from the amino acid sequence of the catalytic site of estradiol 17β-dehydrogenase (E 2 DH) and polyclonal antibodies raised against the enzyme purified from human placenta, clones were isolated from a λgt11 human placental cDNA library. A 327-amino acid sequence was deduced from cDNA sequencing. Two mRNA species have been identified in poly(A) + RNA from human placenta, a major species migrating at 1.3 kb while a minor one is found at approx. 2.2 kb. Primer extension and S 1 nuclease analysis indicate that the major mRNA species starts 9–10 nucleotides while the minor mRNA starts 971 nucleotides upstream from the ATG initiating codon, respectively. Sequence analysis of the longest cDNA clone (2092 bp) shows that it possesses identical coding and non-coding sequences in the regions of overlap with the shorter cDNA clones. The 32 P-labeled 5' non-coding fragment hybridizes only to the 2.2 kb band, thus providing evidence for the existence of two distinct mRNA species which differ in their 5' noncoding regions. Using hp E 2 DH-36 cDNA as a probe for in situ hybridization of translocated chromosomes, the human E 2 DH gene was localized to the q11–q12 region of chromosome 17.