The detergent solubility properties of a malarial (Plasmodium knowlesi) variant antigen expressed on the surface of infected erythrocytes
✍ Scribed by Russell J. Howard; John W. Barnwell
- Publisher
- John Wiley and Sons
- Year
- 1984
- Tongue
- English
- Weight
- 907 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Four detergents have been compared for identification of the Plasmodium knowlesi variant antigen on infected erythrocytes by immunoprecipitation analysis. Erythrocytes infected with late trophozoite and schizont forms of cloned asexual parasites were labeled by lactoperoxidase-catalyzed radioiodination and extracted either with the anionic detergents sodium dodecyl sulfate (SDS) or cholate, the neutral detergent Triton X-100, or the zwitterion 3-[(3-~holamidopropyl)dirnethylammoniol-1-propane sulfonate (CHAPS). After addition of Triton X-100 to SDS and cholate extracts, parallel irnmunoprecipitations of the four extracts were performed using rhesus monkey antisera of defined agglutinability . Identical results were obtained with clone Pkl(A+), which has 1251-variant antigens of M, 210,000 and 190,000, and with clone Pkl(B+)l +, which has variant antigens of M, 200,000-205,000. SDS yielded maximal levels of immunoprecipitated 1251variant antigens. Variant-specific imrnunoprecipitation was detected in some experiments with Triton X-100 and cholic acid but with significantly lower recovery than with SDS. CHAPS extraction did not yield the variant antigens on immunoprecipitation. The variant antigens could also be identified in Triton X-100insoluble material by subsequent extraction with SDS, indicating that failure to recover these proteins in the Triton X-100-soluble fraction is due to failure of this detergent to extract the variant antigens rather than to degradation during extraction. We suggest that the I2%variant antigens either have a structure that renders them intrinsically insoluble in Triton X-100, cholate, or CHAPS, or that they are associated in some way with host cell membrane components that also resist solubilization by these detergents.