Do low complexity segments replace introns?
This question is prompted by the observation that, whereas increase in total low complexity segment length is directly related to gene length (Figs. 1c,d), in P. falciparum this does not apply to intron length (Figs. 1a,b). The present work shows that quantitatively (with respect to absolute lengths) introns and low complexity segments are not mutually exchangeable (Figs. 1e, f). Furthermore, the low complexity segments tend to be of high AG% (purine-loading of ORFs), whereas introns tend to be of low AG% (i.e. tending towards pyrimidine-loading [34,35]). The question might be further addressed by comparing intron locations in regular eukaryotic genes (small exons and multiple introns), with the positions of low complexity segments in homologous genes of P. falciparum that have no, or few, introns. However, intron locations often show no relationship to defined protein functional domains [ 32,33], whereas low complexity segments predominate between defined protein functional domains (i
