Detection and Immunolocalization of Human Erythrocyte Spectrin Immunoanalogues in Toxoplasma gondii (Protozoan, Parasite)

Abstract

We demonstrated here the presence of proteins antigenically related to human erythroid spectrin in the parasitic protozoan Toxoplasma gondii. A high molecular weight doublet (M(r) 245-240,000), present in equimolar ratio, and low molecular weight poly-peptides (M(r) 75,000) were reacted with monoclonal and polyclonal anti-human erythroid spectrin antibodies on electroblotted nitro-cellulose sheets. Indirect immunofluorescence assay clearly showed that these proteins were localized in the anterior pole of the organism. Immunogold staining further revealed specific labeling of conoid, rhoptries, micronemes, and dense granules of the apical complex. The presence of the M(r) 245-240,000 doublet and the M(r) 75,000 spectrin-like proteins in the anterior pole of T. gondii may probably be consistent with a structural stabilizer function in its organelles which are suspected to be involved in the process of host cell invasion.

Cytoskeletal changes in Eimeria bovis-infected host endothelial cells during first merogony

“…Not only host cell spectrin but also spectrin of E. bovis sporozoites and released merozoites were stained by the monoclonal antibodies. To our reported knowledge, the presence of spectrin in E. bovis is missing from the literature, but spectrin-like proteins have been already decribed in the anterior part of T. gondii (Ghazali et al 1995).…”

Specificity of commercial anti-spectrin antibody in the study of fungal and Oomycete spectrin: Cross-reaction with proteins other than spectrin

“…The proteins recognized have been reported as spectrin-like proteins in protists (Hemphill et al, 1991;Ghazali et al, 1995;Holzinger et al, 1999), plants (Michaud et al, 1991;Faraday and Spanswick, 1993;Bisikirska and Sikorski, 1997;De Ruijter et al, 1998, Oomycetes (Kaminskyj and Heath, 1995) and fungi (Degousée et al, 2000;Slaninová et al, 2003;Cotado-Sampayo et al, 2006). However, our search for the bona fide spectrin in fungal-specific and general databases (Broad Institute Database, MIPS and NCBI) using conserved sequence of CH-homology domain did not show any gene coding for spectrin.…”

Isolation and identification of actin-binding proteins in Plasmodium falciparum by affinity chromatography

“…In several unicellular organisms, non-erythroid spectrins have been described. In Toxoplasma gondii two proteins 240-245 kDa, immunogenically related to human spectrin, were localized by immunofluorescence on the apical end of the parasite (tachyzoite) (Ghazali et al 1995). In trophozoites of Gregaria blaberae, a spectrin-like protein was detected by immunobloting (Ghazali et al 1989).…”

“…The other one, a protein of 13 kDa, could be a profilin, although we were not able to confirm its identity. Profilin has been found in most eukaryotic cells playing an important role in the regulation of the polymerization kinetics of actin fibers (Goldschmidt-Clermont et al 1990, Machesky & Pollard 1993.…”