Human histamine H2 receptor gene: multiple transcription initiation and tissue-specific expression

We have characterized the genomic structure of 12.3 kb of the 5'-flanking region of the human histamine H2 receptor gene. The multiple transcription initiation sites of the human histamine H2 receptor gene were mapped utilizing the 5'-end cap structure of mRNA. We found that a 85 bp segment (-610-(-)525 bp) immediately upstream of the initiation site exhibits a strong promoter activity in the gastric adenocarcinoma, MNK45, expressing human histamine H2 receptor. A 4.8 kb transcript of the human histamine H2 receptor gene was found in the placenta, spinal cord, lymph node and bone marrow in addition to the previously reported tissues including the heart, brain and stomach, whereas a 1.8 kb transcript was observed in almost all tissues examined. 3'-rapid amplification of cDNA ends revealed the corresponding length of the 3'-untranslated region. These results suggest that the 3'-untranslated region may be involved in the differential expression.