STR (Medicago truncatula, D3GE74) – curation notes

2026-10-02 research journal

Sources: UniProt D3GE74, Falcon deep research (STR-deep-research-falcon.md), cached abstracts
(PMID:20453115, 26511916, 22077667, 30292683, 28380681 abstract-only; PMID:34618047, 37717076 full text).

Identity and architecture

• Half-size ABCG transporter, positionally cloned from the str mutant PMID:20453115.
• Conserved clade restricted to AM hosts PMID:20453115.
• Do not confuse with MtABCG59 (full-size, strigolactone secretion) [file:MEDTR/STR/STR-deep-research-falcon.md].

Complex and location

• Heterodimer with STR2 (A9YWR6) at the periarbuscular membrane PMID:20453115. BiFC STR–STR negative (basis of the NOT homodimerization row).
• GO note: GO:0085042 periarbuscular membrane has ancestors host cell membrane / host cellular component, NOT plasma membrane (checked QuickGO). So the plasma membrane rows are not redundant in the graph.

Process

• str: arbuscules stunted, AM fails; nodulation normal PMID:20453115.
• Rice STR1/STR2 phenocopy; strigolactones unlikely substrates PMID:22077667.

Substrate (unresolved)

• FatM/RAM2 make 16:0 beta-MAG; model is export across the PAM PMID:28380681.
• Expert review: no direct proof PMID:34618047.
• STR–STR2 co-overexpression in Arabidopsis atwbc11-4 increased cutin PMID:37717076 – heterologous, indirect.
• Decision: keep MF at ABC-type transporter activity; no lipid-transporter MF or lipid export BP proposed (NEW count 0).

Regulation

• RAM1-dependent PMID:26511916; WRI5a binds STR AW-boxes PMID:30292683; ERM1 binds STR/STR2 promoters, ERF12 feedback PMID:37717076.

Curation decisions

• protein binding (IPI, STR2) -> MODIFY to protein heterodimerization activity GO:0046982.
• ATP binding, ATP hydrolysis, membrane, response to symbiotic fungus (x2) -> KEEP_AS_NON_CORE.
• All others ACCEPT, including NOT nodulation and NOT homodimerization.