NOT1-G

NOT1-G (PF3D7_1103800) is a Plasmodium-specific scaffold subunit associated with the CAF1/CCR4/NOT complex that functions in the stage-specific control of translational repression during malaria parasite transmission (PMID:38352447, PMID:39777415). In P. yoelii female gametocytes, NOT1-G engages the DDX6-family helicase DOZI, and this interaction is a defining feature of the repressed state; upon fertilization, DOZI exchanges NOT1-G for the canonical NOT1 in the zygote, a compositional switch within the DOZI/CITH/ALBA complex that provides a mechanistic trigger for the global release of stored mRNAs from translational repression during the host-to-vector transition (PMID:38352447, PMID:39777415). Its membership in the PfCaf1-CCR4-NOT complex was first predicted bioinformatically in P. falciparum (PMID:26525978). Beyond this DOZI-dependent scaffold role in transmission-stage translational control, no direct enzymatic activity, substrate mRNA repertoire, or structural detail for NOT1-G has been characterized in the available corpus.

1. 2015 Low

   Before any functional work, it was unknown whether NOT1-G belonged to the parasite CCR4-NOT machinery at all; comparative interactome analysis placed it within the PfCaf1-CCR4-NOT complex, establishing a candidate role in mRNA regulation.

   Evidence Bioinformatic comparative interactome analysis and protein-protein interaction network construction in P. falciparum

   PMID:26525978

   Open questions at the time

   • Computational prediction only, with no direct experimental validation of NOT1-G specifically
   • No demonstration of physical interaction or subcellular context
   • No stage-specific or functional assignment
2. 2024 Medium

   It was unknown how repressed maternal mRNAs are released from translational silencing at fertilization; proximity proteomics showed DOZI interacts with NOT1-G in female gametocytes and swaps to canonical NOT1 in zygotes, providing a compositional-switch model for derepression during transmission.

   Evidence TurboID proximity proteomics across gametocyte and zygote stages, cross-validated by expansion and structured illumination microscopy in P. yoelii (preprint)

   PMID:38352447

   Open questions at the time

   • Preprint form at time of entry; proximity proteomics infers association, not direct binding
   • Does not identify which mRNAs are controlled by the NOT1-G-containing complex
   • Mechanism driving the NOT1-G-to-NOT1 exchange is not defined
3. 2025 Medium

   The gametocyte-to-zygote exchange model was extended and quantified, confirming that DOZI shifts from NOT1-G to canonical NOT1 as part of a remodeling of the DOZI/CITH/ALBA complex consistent with a fertilization-triggered release of translational repression.

   Evidence TurboID proximity proteomics with quantitative DIA-MS comparing female gametocytes and zygotes, supported by comparative transcriptomics and proteomics in P. yoelii

   PMID:39777415

   Open questions at the time

   • Single-lab study relying on proximity labeling rather than direct structural/biochemical reconstitution
   • Functional consequence of removing NOT1-G on mRNA derepression not directly tested
   • Structural basis for DOZI selecting NOT1-G versus NOT1 unresolved

• The direct molecular activity of NOT1-G, its specific mRNA targets, and the structural basis for its stage-specific exchange with canonical NOT1 remain undetermined.
• No defined biochemical or scaffolding activity for NOT1-G in isolation
• No identified repressed transcript repertoire dependent on NOT1-G
• No structural model of the DOZI–NOT1-G interaction or the exchange mechanism