hsp 70-like protein in rhesus erythrocyte cytosol and its interactions with membrane skeleton under heat and pathologic stress.

The rhesus erythrocytes were examined for the presence of protein(s) similar to the 70-kDa class of heat shock proteins (hsp 70). Also, interactions of these proteins with the erythrocyte membrane were studied under heat stress. These cells in their cytosol contained at least two proteins of about 70 kDa molecular mass; one of which closely resembled the hsp 70 family of proteins. This protein under normal conditions localized mainly in the cytosol, but it had a strong tendency to bind the membrane under heat stress. The binding was almost exclusively restricted to the membrane skeleton and seemed to involve primarily the hydrophobic interactions. A 70-kDa protein immunologically similar to the above protein(s) was detected also in the membranes of rhesus erythrocytes harboring the schizont stage of the simian malarial parasite Plasmodium knowlesi. From these results, we conclude that hsp 70-like proteins in the mature mammalian erythrocytes could perhaps play an important role in protecting the cells under stress by stabilizing the membrane skeleton through their interactions with skeletal proteins.