The Journal of Cell Biology, Vol 97, 196-201, Copyright © 1983 by The Rockefeller University Press
Membrane-associated phosphoproteins in Plasmodium berghei-infected murine erythrocytes
MF Wiser, PA Wood, JW Eaton and JR Sheppard
Normal and Plasmodium berghei (NYU-2 strain)-infected murine erythrocytes
display substantially different patterns of plasma membrane phosphoproteins
phosphorylation. Intact erythrocytes (normal and parasite infected)
incubated with 32Pi and isolated washed erythrocyte plasma membranes
incubated with gamma-32P-ATP were analyzed for phosphoproteins by SDS PAGE
and autoradiography. Two new phosphoproteins of molecular weight 45,000
(pp45) and 68,000 (pp68), which are absent in normal erythrocyte membranes,
are associated with the membranes of infected erythrocytes subjected to
both intact-cell and isolated-membrane phosphorylation conditions.
Two-dimensional gel electrophoresis indicates that pp45 and pp68 are of
parasite origin. Partial or complete proteolytic digestion reveals that
pp45 is phosphorylated at similar amino acid residues both in intact cells
and in isolated membranes. The pp45 phosphoprotein can be detected at as
low as 3% parasitemia and its phosphorylation is not affected by 10 microM
cAMP, 1 mM Ca2+, or 5 mM EGTA. Extraction of isolated washed plasma
membranes with 0.5% Triton X-100 or 0.1 M NaOH indicates that pp45 is
detergent insoluble and only partially extractable with NaOH, suggesting
that pp45 is closely associated with the host erythrocyte plasma membrane.
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