Tissue specific expression of betaine-homocysteine methyltransferase (BHMT), and chromosomal localization of the human gene

We have prepared antibodies against porcine liver BHMT, and recently cloned cDNAs encoding the porcine and human enzyme. Porcine tissues were tested for BHMT expression by enzyme activity measurements, and Western analysis. Porcine liver and kidney were the only organs that had immune-detectable levels of BHMT protein, and expressed high levels of enzyme activity. Porcine pancreas, brain, heart, lung, and spleen were essentially devoid of enzyme activity and had no immuno-detectable protein. Both BHMT activity measurements and Western analysis indicate that BHMT is expressed in porcine kidney cortex, and not the medulla. Human tissues were tested for BHMT expression by Northern analysis. Human liver and kidney were the only organs that expressed BHMT mRNA. Human pancreas, brain, heart, skeletal muscle, spleen, and placenta were devoid of BHMT mRNA. BHMT was mapped to human chromosome 5 by PCR amplification using human BHMT-specific primers and chromosome specific human-rodent somatic cell hybrid panels. Refinement of the physical localization of the gene was obtained by screening a yeast artificial chromosome library. Funded by AHA (IL affiliate), and ILSI (N. America).