ROP14

ROP14 (PF3D7_0613300) is a rhoptry bulb protein of Plasmodium merozoites implicated in the post-invasion phase of the erythrocyte invasion program (PMID:23049965). In P. falciparum blood-stage merozoites it localizes to the rhoptry bulb subcompartment and is released only after invasion is complete, distinguishing it temporally from rhoptry neck proteins that discharge earlier during moving-junction formation (PMID:23049965); an earlier annotation of ROP14 as a transporter was retracted on the basis of these localization and functional data (PMID:35811673). Across life-cycle stages and species ROP14 is repeatedly found in the apical rhoptry neighborhood, being captured in proximity interactomes of the rhoptry bulb proteins CERLI1 and CERLI2 in P. falciparum schizonts (PMID:35140336) and of the rhoptry neck proteins RON6 and RON12 in P. berghei merozoites and sporozoites (PMID:40996030, PMID:41668734). In P. berghei, ROP14 is dispensable for asexual blood-stage replication, as disruption of the locus produces no growth defect (PMID:35202423), and its transcription is directly activated by the AP2 factor PbSIP2, which binds an RGTGCA cis-element in the rop14 promoter (PMID:40117352). ROP14 also undergoes lysine methylation in P. falciparum asexual stages (PMID:27762281). Beyond this rhoptry localization, invasion-timed release, and transcriptional control, no enzymatic activity, receptor, or downstream effector of ROP14 has been mechanistically defined in the available corpus.

1. 2012 Medium

   Establishing where and when ROP14 acts was the first question, and endogenous tagging placed it in the rhoptry bulb with release timed to after invasion, separating it functionally from neck proteins that act during junction formation.

   Evidence endogenous gene-tagging and high-definition fluorescence imaging during erythrocyte invasion in P. falciparum

   PMID:23049965

   Open questions at the time

   • What ROP14 does after post-invasion release is undefined
   • No binding partner or substrate identified
   • No structural information
2. 2012 Low

   The prior annotation of ROP14 as a transporter was overturned, correcting its functional classification to a rhoptry protein.

   Evidence literature curation and re-analysis of localization/function data in P. falciparum 3D7

   PMID:35811673

   Open questions at the time

   • Negative reclassification based on secondary curation, no new direct experiment
   • Positive function not established
3. 2016 Low

   A post-translational modification of ROP14 was uncovered, showing it is lysine-methylated in asexual stages.

   Evidence anti-methyl-lysine immunoprecipitation and LC-MS/MS in P. falciparum

   PMID:27762281

   Open questions at the time

   • Single MS identification, no writer/eraser/reader defined
   • No functional consequence of methylation established
4. 2021 Low

   ROP14 protein and its encoding DNA were found selectively packaged and protected within parasite-derived extracellular vesicles, raising the question of a non-canonical extracellular role.

   Evidence DNase I protection assay on purified EVs and PCR in P. falciparum

   PMID:29215015

   Open questions at the time

   • Single PCR-based detection
   • No functional consequence of rop14 DNA packaging established
5. 2022 Medium

   Whether ROP14 is required for blood-stage growth was tested, and knockout in P. berghei showed it is dispensable for asexual replication.

   Evidence CRISPR/Cas9 gene disruption with genotyping and growth monitoring in P. berghei

   PMID:35202423

   Open questions at the time

   • Dispensability in asexual stages does not exclude a role in other stages
   • No molecular function assigned
6. 2022 Low

   Proximity proteomics placed ROP14 in the molecular neighborhood of rhoptry bulb proteins CERLI1 and CERLI2, providing the first partner context.

   Evidence DiQ-BioID proximity biotinylation and LC-MS/MS in P. falciparum schizonts

   PMID:35140336

   Open questions at the time

   • Single proximity experiment, no reciprocal validation
   • Proximity does not establish direct interaction
7. 2023 Low

   ROP14 was placed in the RON12 proximity network in sporozoites, extending its rhoptry association beyond blood-stage merozoites into the sporozoite stage.

   Evidence UltraID proximity biotinylation and LC-MS/MS in P. berghei sporozoites

   PMID:41668734

   Open questions at the time

   • Single proximity experiment, no direct functional validation for ROP14
   • Sporozoite-stage role undefined
8. 2025 High

   How rop14 expression is controlled was resolved by showing the AP2 factor PbSIP2 directly binds an RGTGCA element in the promoter and is required for full transcription, establishing direct transcriptional regulation.

   Evidence ChIP-seq, DIP-seq, CRISPR/Cas9 cis-element mutation, ChIP-qPCR and RT-qPCR in P. berghei

   PMID:40117352

   Open questions at the time

   • Links regulation to transcript level but not to a protein function
   • Downstream biological consequence of PbSIP2-driven rop14 expression not defined

• The core molecular function of ROP14 remains unknown: no enzymatic activity, receptor, host substrate, or downstream effector has been defined despite established rhoptry localization, post-invasion release, and transcriptional control.
• No biochemical activity assigned
• No direct binding partner validated
• Role after post-invasion release into the host cell unknown