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ALMUDENA CROOKE Y COLS. AN. R. ACAD. NAC. FARM.

protein size change across parasite life cycle by protein processing
or by alternative splicing. To this respect, different sizes of mRNA
G6PD-6PGL have been observed in parasites in the ring and tropho-
zoite stages (31). Thus, there seems to be specific P. falciparum
mechanisms for processing this mRNA, controlled by the parasite’s
development cycle, which could be unique or shared with other genes
(32, 33). The 69 kDa band could coincide with the C-terminal end of
the protein corresponding to G6PD activity in such a way that it
would not show the N-terminal end that corresponds to the 6PGL
activity. Based on the data shown, we can hypothesize a controlled
pattern of PfG6PD-6PGL processing during parasite maturation as
depicted in Figure 4.

FIGURE 4. Hypothetical processing of G6PD-6PGL. The protein product sizes
observed by immunodetection analysis across the intraerytrocytic P. falciparum life

cycle could be explained by two steps of controlled maturation of the protein to
take apart, optimize and recycle, the two functional enzymatic activities in the

parasite cell.

An independent role of the 6PGL function has been addressed,
and although its 6-phosphogluconolactone substrate is highly
unstable in vitro, some increase in the efficiency of the pathway
may be evident (21,34). To this respect, the lactonase activity

638