A cDNA encoding Tc-MUC-5, a mucin from Toxocara canis larvae identified by expression screening
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Date
2001Author
Doedens, Andrew
Loukas, Alex
Maizels, Rick
Metadata
Abstract
Toxocara canis is an ascarid nematode parasite of canids. Larvae infect a wide range of accidental hosts including
humans, in whom they are the aetiologic agent of visceral and ocular Larva migrans. The labile surface coat of T.
canis larvae consists of a family of mucin glycoproteins termed TES-120, for which the cDNAs have recently been
cloned. In this paper, we describe the identification of a novel cDNA (Tc-muc- 5) encoding an apomucin by
expression screening of a cDNA library with antiserum raised to T. canis excretory/secretory products, and compare
the predicted Tc-MUC-5 protein with those of other T. canis mucins (Tc-MUC-1–Tc-MUC-4) that include the
TES-120 surface coat glycoproteins. Tc-MUC-5 has both a larger open reading frame and a more divergent sequence
than the other T. canis mucins. It contains a putative signal peptide followed by two six-cysteine (SXC) domains, an
extended threonine-rich central mucin core domain and two C-terminal SXC domains. Amino acid composition
analysis of secreted TES-120 glycoproteins revealed a distinct lack of lysine residues; while this finding is in agreement
with the primary sequences of Tc-MUC-1–Tc-MUC-4, Tc-MUC-5 is conspicuous by its relative abundance of lysines
(6.7%), suggesting that this protein is not part of the TES-120 family of surface coat proteins.