PABP2

PABP2 (PF3D7_0923900) is a nuclear poly(A)-binding protein of Plasmodium that recognizes poly(A) RNA and participates in post-transcriptional mRNP regulation (PMID:29359180, PMID:33906926). In the P. yoelii ortholog, PABP2 binds poly(A) RNA specifically and strongly and localizes to the nucleus during blood stages, distinguishing it from the cytosolic PABP1 (PMID:29359180). In P. falciparum, its poly(A) recognition is sensitive to RNA modification: PABP2 is enriched on non-methylated poly(A) RNA but excluded from m6A-methylated RNA, indicating that adenosine m6A methylation inhibits its binding (PMID:33906926). PABP2 is incorporated into translationally repressive mRNP complexes in a stage-specific manner: in nutritionally stressed P. falciparum schizonts it associates with PfDOZI, CITH, and PAIP1 in stress granule-like mRNPs (while the germ cell granules of gametocytes instead contain PABP1) (PMID:38702310), and in P. yoelii it is a proximal interactor of ALBA4 within the DOZI/CITH/ALBA regulatory complex across female gametocytes and zygotes (PMID:39777415). Beyond these binding, localization, and complex-membership observations, no dedicated functional or loss-of-function characterization of PABP2 itself has been reported in the available corpus.

1. 2018 Medium

   Establishing that this poly(A)-binding protein is a nuclear, poly(A)-specific factor distinct from the cytosolic PABP1 defined its basic biochemical identity and subcellular compartment.

   Evidence Multiple in vitro poly(A)-binding assays and indirect immunofluorescence in P. yoelii blood stages

   PMID:29359180

   Open questions at the time

   • Binding shown for the P. yoelii ortholog; not directly demonstrated for P. falciparum PF3D7_0923900 in this study
   • No structural basis for poly(A) recognition determined
   • No functional consequence of nuclear localization established
2. 2021 Medium

   Showing that PABP2 binding is blocked by m6A methylation linked its RNA recognition to the RNA epitranscriptome, implying it reads a specific chemical state of poly(A) sequences.

   Evidence Quantitative TMT proteomics of methylated vs. non-methylated RNA oligonucleotide pulldowns in P. falciparum blood stages

   PMID:33906926

   Open questions at the time

   • Whether m6A exclusion alters mRNA fate or translation regulation was not tested for PABP2
   • Single-lab, single-method observation without reciprocal in vivo validation
3. 2024 Low

   Identifying PABP2 in stress-induced schizont mRNPs with PfDOZI, CITH, and PAIP1 placed it in translational-repression granules and revealed stage-specific use of PABP2 versus cytosolic PABP1.

   Evidence PfDOZI interactome by quantitative mass spectrometry across life stages in P. falciparum

   PMID:38702310

   Open questions at the time

   • Single interactome MS approach without reciprocal Co-IP or functional follow-up specific to PABP2
   • Direct versus indirect association within the mRNP unresolved
   • Role of PABP2 in granule assembly or mRNA fate not tested
4. 2025 Low

   Detecting PABP2 as a proximal ALBA4 interactor in gametocytes and zygotes extended its mRNP association into the DOZI/CITH/ALBA regulatory complex spanning the transmission event.

   Evidence TurboID-based proximity proteomics (DIA-MS) of ALBA4 and DOZI baits in P. yoelii female gametocytes and zygotes

   PMID:39777415

   Open questions at the time

   • Proximity labeling identifies neighbors, not direct binding; no reciprocal validation for PABP2
   • No functional or loss-of-function study of PABP2 in this complex
   • Contribution of PABP2 to translational repression during transmission unknown

• The direct molecular function of PABP2 within its mRNP complexes and the phenotypic consequence of its loss remain undetermined.
• No genetic knockout or knockdown of PABP2 reported
• Whether PABP2 actively represses translation or merely marks poly(A) tails is untested
• Mechanism connecting nuclear localization to cytoplasmic/granule mRNP roles unresolved