1.C.15 The Whipworm Stichosome Porin (WSP) Family

The human parasitic nematode, Trichuris trichiura (whipworm), infects about 20% of the world''s population, causing growth defects and impaired cognition. T. muris is the equivalent mouse parasite. A characteristic stichosome encloses much of the worm, and the major protein of stichosome extracts is WSP, a protein of 40-100 kDa which is capable of inducing pores in planar lipid bilayers. It consists of 9 (TT50) to 17 (TT95) tandemly arranged domains of 50-51 amino acyl residues in which cysteine spacing is highly conserved. This domain is called the ''WAP-type'' four disulfide core domain. These repeats are found in a variety of proteins including the ovulatory protein-2 precursor (gbU67854) and secretory leukocyte protease inhibitor (spP97430). There is an N-terminal 23 hydrophobic amino acid signal sequence used for secretion.

Maintenance of attachment to the host gut requires continual invasion of new epithelia due to continuous sloughing of the gut wall. WSP appears to facilitate attachment and maintenance of the parasite in the gut, presumably by facilitating transport of small molecules (ions) across the epithelial membrane.



Barker, G.C. and D.A.P. Bundy (1999). Isolation of a gene family that encodes the porin-like proteins from the human parasite nematode Trichuris trichiura. Gene 229: 131-136.

Drake, L.J., G.C. Barker, Y. Korachev, M. Lab, H. Brookes and D.A.P. Bundy (1998). Molecular and functional characterisation of a recombinant protein of Trichuris trichiura. Proc. R. Soc. Lond. B 265: 1559-1565.

Drake, L.J., Y. Korachev, L. Bashford, M. Djamgoz, D. Wakelin, F. Ashall and D.A.P. Bundy (1994). The major secreted protein of the whipworm, Trichuris, is a pore-forming protein. Proc. R. Soc. Lond. B 257: 255-261.

Drenth, J., B.W. Low, J.S. Richardson and C.S. Wright (1980). The toxin-agglutinin fold. A new group of small protein structures organized around a four-disulfide core. J. Biol. Chem. 255: 2652-2655.


TC#NameOrganismal TypeExample
1.C.15.1.1Putative porin TT95 (WSP) Nematodes TT95 (WSP) of Trichuris trichiura

Caltrin II, a Ca2+ transport inhibitor.


Caltrin II of Cavia porcellus (guinea pig)