Structural organization of the gene encoding the neuroendocrine chaperone 7B2

The neuroendocrine-specific polypeptide 7B2 is a constituent of the regulated secretary pathway. Recently, 7B2 was found to function as a molecular chaperone for prohormone convertase PC2. This report describes the genomic organization of the 7B2 gene which consists of six exons. Exon I corresponds to the 5'-untranslated mRNA region, while exons 2 and 3 encode the signal peptide and the amino-terminal half of the 7B2 protein that is distantly related to a subclass of molecular chaperones. The carboxy-terminal half of 7B2, responsible for its inhibitory action on PC2, is encoded by exons 4-6. Primer-extension analysis showed that the human 7B2 gene is transcribed from multiple transcription-initiation sites. The human 7B2 gene promoter contains a cAMP-responsive element, an AP-1 site, and several Pit-1/GHF-1-binding domains and heat-shock-element-like sequences but no obvious TATA or CAAT boxes. Of further interest is the finding of two DNA elements which are common to the promoter regions of the 7B2 gene and other genes selectively expressed in neuroendocrine tissues.