Structure and polymorphism of the Chironomus thummi gene encoding special lobe-specific silk protein, ssp160.
cDNA encoding Chironomus thummi ssp160 was used to isolate a genomic clone that hybridized in situ to band A2b on polytene chromosome IV, the site of the ssp160 gene. DNA sequencing, primer extension and gene/cDNA nucleotide sequence alignment revealed the gene contains six exons and five introns; 70% of ssp160 is encoded in exon 3. Variations between cDNA and gene sequences led to the design of a polymerase chain reaction, restriction fragment length polymorphism assay that was subsequently used to demonstrate the existence of polymorphic alleles whose distribution varied between geographically separated populations of larvae. The polymorphism is associated with codon deletions in a six-amino-acid repeat containing an N-linked glycosylation motif. These deletions may have resulted from slipped-strand mispairing during DNA replication.
Berezikov
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Laboratory of Cell Biology, Institute of Cytology and Genetics, 630090, Novosibirsk, Russia.
Blinov
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AG
Scherbik
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S
Cox
C K
CK
Case
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ST
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002683:Chironomidae / Q000235:genetics* / Q000254:growth & development; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D005091:Exons; D006023:Glycoproteins / Q000235:genetics*; D019476:Insect Proteins; D007438:Introns; D007814:Larva; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D012091:Repetitive Sequences, Nucleic Acid; D012471:Salivary Proteins and Peptides / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D047011:Silk
D006023:Glycoproteins; D019476:Insect Proteins; D012471:Salivary Proteins and Peptides; D047011:Silk; C099286:ssp160 protein, silk