M. Dyer et K. Day, Expression of Plasmodium falciparum trimeric G proteins and their involvement in switching to sexual development (vol 108, pg 67, 2000), MOL BIOCH P, 110(2), 2000, pp. 435
Both cholera and pertussis toxins were used to label and study the expressi
on of heterotrimeric G protein alpha subunits in Plasmodium falciparum extr
acts. Expression of these proteins is developmentally regulated throughout
the erythrocytic cycle with peak expression during early asexual developmen
t and in mature sexual stages. Treatment of P. falciparum cultures with cho
lera toxin causes an increase in conversion to sexual development, and at t
he same concentration has a marginal inhibitory effect on asexual growth an
d division. Through precise synchronisation of the parasites' asexual cell
cycle, we have defined the period of sensitivity to this induction at aroun
d the time of invasion, one cycle before the development of the sexual form
. Fluorescent microscopy confirmed that access of the toxin to the parasite
is limited to the invasive form - the free merozoite, while further labell
ing studies revealed expression of a single G protein cr subunit in these s
tages. These observations are consistent with the view that a G protein-dep
endent signal transduction pathway is involved in coupling the parasite's e
nvironment to commitment to sexual development (gametocytogenesis). This me
ans of artificially stimulating the pathways leading to sexual development
can now be used to biochemically follow the activation of the signalling pa
thways involved. (C) 2000 Elsevier Science B.V. All rights reserved.