Premium
The insect immune protein scolexin is a novel serine proteinase homolog
Author(s) -
Finnerty Casey M.,
Granados Robert R.,
Karplus P. Andrew
Publication year - 1999
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.8.1.242
Subject(s) - manduca sexta , subfamily , serine protease , biology , serine , complementary dna , biochemistry , peptide sequence , chymotrypsin , conserved sequence , insect , phosphorylation , enzyme , protease , gene , trypsin , ecology
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.