Bombyxin F1 gene: structure and expression of a new bombyxin family gene that forms a pair with bombyxin B10 gene.

Bombyxin F1 gene, a new bombyxin family gene, has been identified. The F1 gene forms a pair with bombyxin B10 gene with an opposite transcriptional orientation and the gene pair F1/B10 is located between bombyxin gene pairs B9/C1 and A7/B7 in a bombyxin gene cluster. The nucleotide sequence of the F1 gene and its deduced amino acid sequence deviate moderately from those characterized previously for the family-A, family-B, family-C, family-D, and family-E bombyxin genes; the bombyxin F1 gene and preprobombyxin F1 share no more than 62% and 53% sequence identities with other bombyxin members, respectively. Harr-plot analysis indicated that the spacer of the F1/B10 gene pair has low sequence similarity with that of other bombyxin gene pairs characterized. The bombyxin F1 mRNA in Bombyx mori brain was shown to locate in four pairs of medial neurosecretory cells, which also produce other bombyxin family mRNAs. Genomic Southern hybridization indicated that the Bombyx haploid genome contains a single copy of the family-F bombyxin gene.