Structures and organization of major plasma protein genes of the silkworm Bombyx mori.
In the silkworm, Bombyx mori, a group of structurally related proteins, termed 30K proteins, accumulate in the hemolymph of the last instar larvae. We have isolated and characterized three genes, each of which encodes a distinct 30K protein component. Each 30K protein gene is composed of a short first exon and a protein-coding second exon interspersed by a single intron. The transcription initiation site of the 30K protein mRNA was identified at the nucleotide level. A typical TATA box exists some 30 base-pairs upstream from the transcription initiation site. The 5'-flanking region of each gene also contains octamer-like sequences. Restriction mapping analyses revealed that the cloned 46 x 10(3) base-pair region of the chromosomal DNA bears three 30K protein genes. Several copies of highly reiterated retrotransposon-like sequences are present around the 30K protein genes. S1 nuclease protection analysis provided evidence that the biosynthesis of 30K protein is regulated in a stage-specific manner at the transcriptional level in the fat body.
Mori
S
S
Department of Biology, Tokyo Metropolitan University, Japan.
Izumi
S
S
Tomino
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S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics*; D005796:Genes; D006458:Hemolymph / Q000378:metabolism; D007814:Larva; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics*; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D016385:TATA Box; D014158:Transcription, Genetic
D011506:Proteins