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The insect immune protein scolexin is a novel serine proteinase homolog.

ABSTRACT: Scolexin is a coagulation-provoking plasma protein induced in response to bacterial or viral infection of larval Manduca sexta, a large lepidopterous insect. Here we report the isolation and sequencing of two cDNA clones that code for scolexin isoforms sharing 80% sequence identity. The scolexin sequences have low but recognizable sequence similarity to members of the chymotrypsin family and represent a new subfamily of chymotrypsin-like serine proteinases. Comparison with known structures reveals the conservation of key catalytic residues and a possible specificity for small nonpolar residues. Most remarkable is the absence of a canonical activation peptide cleavage site. This suggests that the regulation of scolexin activity will involve a novel activation mechanism.

SUBMITTER: Finnerty CM

PROVIDER: S-EPMC2144095 | biostudies-other | 1999 Jan

REPOSITORIES: biostudies-other

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The insect immune protein scolexin is a novel serine proteinase homolog.

Finnerty C M CM Karplus P A PA Granados R R RR

Protein science : a publication of the Protein Society 19990101 1

Scolexin is a coagulation-provoking plasma protein induced in response to bacterial or viral infection of larval Manduca sexta, a large lepidopterous insect. Here we report the isolation and sequencing of two cDNA clones that code for scolexin isoforms sharing 80% sequence identity. The scolexin sequences have low but recognizable sequence similarity to members of the chymotrypsin family and represent a new subfamily of chymotrypsin-like serine proteinases. Comparison with known structures revea ...[more]

PMID: 10210202

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