RAM1 (Medicago truncatula, G7L166) curation notes

Session 2026-10-02 (claude-code, PLANT_FUNGAL_INTERACTIONS project)

Sources: UniProt G7L166, falcon deep research, cached abstracts for PMID:23122845, 25971550, 26511916, 27020747, 28596311 and the full text of 26597293. The three GOA source papers are cached as abstracts only.

Identity

• GRAS family protein, GRAS domain 288-673 (UniProt). Not the same as RAM2, which is the GPAT enzyme downstream of RAM1.

Function

• RAM1 is required for Myc but not Nod signalling PMID:23122845
• ram1-1 has a hyphopodium defect PMID:23122845, BUT ram1-3 does not PMID:26511916. Per the deep research, Park et al. compared ram1-1 and ram1-3 side by side and saw the same unbranched-arbuscule phenotype. So the "RAM1 -> RAM2 -> hyphopodium" link is disputed. The main defect is arbuscule branching.
• Targets: RAM2 is a direct target PMID:28596311. RAM1 is required and sufficient for the arbuscule lipid biosynthesis program PMID:28596311. EXO70I, STR and RAD1 depend on RAM1 PMID:26511916. The deep research says Park et al. did not show RAM1 binding to the STR or EXO70I promoters.
• Upstream: in Lotus, a CCaMK-CYCLOPS-DELLA complex activates RAM1 PMID:27020747. Ectopic RAM1 rescues cyclops mutants. In Medicago, DELLAs modulate RAM1 PMID:26511916.
• Pre-symbiotic stage: the response to Myc-LCOs requires both RAM1 and NSP1 PMID:26597293.
• Interactors (from UniProt, citing Park et al. 2015): NSP2 (Q5NE24), RAD1 (G7JMM0), TF80 (G7J1L1), all GRAS proteins.
• Phosphate: ram1-3 is insensitive to phosphate-mediated suppression of colonization PMID:26511916.

Decisions

• MF: kept DNA-binding TF activity (IBA, plus IMP deferring to curator). Direct DNA binding by RAM1 alone is still unresolved; this is listed as a suggested question.
• protein binding x3 changed by MODIFY to protein heterodimerization activity (GRAS-GRAS).
• detection of phosphate ion: MARK_AS_OVER_ANNOTATED. The phenotype shows RAM1 is needed for the phosphate response; it does not show that RAM1 perceives phosphate (necessity vs participation).
• GO:0006357 changed by MODIFY to GO:0045944 positive regulation of transcription by RNA polymerase II.
• Cytoplasm (ISS from Lotus RAM1, plus IEA): KEEP_AS_NON_CORE.
• PMID:25971550 IMP is about the petunia ATA ortholog going by the abstract. Accepted, and the evidence code is flagged as a question.
• No NEW terms. The plant-side process term GO:0036377 is adequate. The "arbuscule formation for nutrient acquisition" terms (GO:0075328 family) are fungus-side terms and do not apply to the plant protein.