MPK3 (Arabidopsis thaliana, Q39023, At3g45640) - curation notes

2026-10-02 - initial review

Sources: UniProt Q39023, MPK3-deep-research-falcon.md, cached publications (all 32 GOA PMIDs cached; many abstract-only), plus newly cached PMID:17259259 (stomata) and PMID:21498677 (WRKY33). Paralog review genes/ARATH/MPK6 used for consistency.

Molecular function

Proline-directed Ser/Thr MAPK; peptide library gives consensus L/P-P/X-S-P-R/K PMID:22631074.
Activated by H2O2 via ANP1 PMID:10717008, ozone with nuclear translocation PMID:15500467, osmotic stress PMID:12220631.

Immunity (project-relevant)

FLS2 cascade PMID:11875555.
Chitin: downstream of CERK1-PBL27 PMID:24750441.
Camalexin: cascade regulates biosynthetic gene transcription, not the chemistry PMID:18378893; via WRKY33 PMID:21498677.
ACS2/ACS6: direct phosphorylation by MPK3 is less secure than by MPK6 (deep research flags early biochemistry identifying MPK6 not MPK3 as direct ACS6 kinase); left as a suggested question.

Development

Stomata PMID:17259259; no stomatal term in GOA for MPK3 - raised as question, not added.
Inflorescence PMID:23263767, ovule PMID:18364464, pollen tube funicular guidance PMID:24717717, stigma receptivity with MPK4 PMID:32890733.
PMID:24717717 explicitly says "mpk3 mpk6 pollen has no developmental defect" -> pollen development IGI marked over-annotated.

Decisions

Camalexin biosynthetic process (IMP) -> MODIFY to GO:1901183 positive regulation of camalexin biosynthetic process (necessity vs participation; project question 3).
MKP2 protein binding -> MODIFY to phosphatase binding (consistent with MPK6). All other protein binding rows REMOVE.
GO:0002221 pattern recognition receptor signaling pathway was considered as NEW but dropped: same-role comparators (MPK6, MKK4, MKK5) lack it, and BIK1 is a receptor-proximal RLCK, not a same-role comparator. Raised as a suggested question.
Stress-response and developmental rows KEEP_AS_NON_CORE.
Stress granule IDA (PMID:30664249) - MPK3 not named in abstract; deferred to curator (KEEP_AS_NON_CORE), consistent with TZF1 recruitment reported in deep research.