SR-MG

SR-MG (PF3D7_1126800) is an alternative splicing factor that regulates sex-specific pre-mRNA splicing during Plasmodium sexual differentiation and transmission. In P. berghei, genetic disruption of the ortholog PbSR-MG perturbs sex-specific alternative splicing and impairs the parasite's ability to differentiate into male gametes and to form oocysts, thereby reducing transmission between vertebrate and insect hosts (PMID:31370870). In P. falciparum, the PfSR-MG transcript is downregulated in Pfsrpk1-knockout stage V gametocytes—and was the only splicing factor so affected—placing SR-MG downstream of the SR-protein kinase PfSRPK1 in gametocyte gene regulation (PMID:36094218). No direct functional experiment on SR-MG itself has been performed in P. falciparum, so its molecular mechanism in this species remains uncharacterized in the available corpus.

1. 2019 Medium

   Established that SR-MG functions as a sex-specific alternative splicing regulator required for parasite transmission, defining the gene's cellular role rather than leaving it a putative splicing factor.

   Evidence Genetic knockout of the P. berghei ortholog PbSR-MG combined with life-cycle-stage RNA-seq and phenotypic readout of male gametogenesis and oocyst formation

   PMID:31370870

   Open questions at the time

   • The direct RNA substrates and splice sites regulated by SR-MG are not defined
   • Molecular mechanism of splice-site selection or spliceosome interaction is untested
   • Findings are in P. berghei; direct loss-of-function in P. falciparum is absent
2. 2022 Low

   Placed SR-MG within a gametocyte gene-regulatory hierarchy by showing its transcript depends on the SR-protein kinase PfSRPK1, but this was a correlative transcriptomic observation, not a functional test of SR-MG.

   Evidence Bulk RNA-seq of wild-type PfNF54 versus Pfsrpk1-knockout P. falciparum stage V gametocytes with differential expression analysis

   PMID:36094218

   Open questions at the time

   • Transcriptomic association only; no direct functional experiment on SR-MG and no evidence of direct regulation versus indirect downstream effect
   • Whether SR-MG protein activity or its own splicing targets change in this context is unknown
   • No demonstration that PfSRPK1 phosphorylates or physically acts on SR-MG

• The direct molecular mechanism of SR-MG in P. falciparum—its RNA targets, spliceosome partners, and the biochemical consequence of its regulation by PfSRPK1—remains undefined.
• No direct loss-of-function or biochemical experiment on SR-MG in P. falciparum
• No identified RNA substrates or interacting spliceosomal components
• No structural or domain-level characterization in the corpus