AHK4 / CRE1 / WOL notes (Q9C5U0, At2g01830)

2026-10-05 review session (cytokinin two-component signaling module)

• Identity checked: UniProt Q9C5U0 AHK4_ARATH (CRE1, WOL, RAW1), At2g01830.
• Deep research tooling failed in this environment; review based on cached publications.
• First identified cytokinin receptor PMID:11234017; cytokinin-dependent histidine kinase activity in yeast PMID:11479382.
• Structure of the CHASE sensor domain with ligands PMID:21964459.
• Bidirectional: kinase with cytokinin, phosphatase toward AHPs without PMID:16753566. The GO:0004721 positive annotation kept as non-core (reverse phosphotransfer, not a hydrolytic phosphatase); the EC 3.1.3.16-derived GO:0004722 Ser/Thr phosphatase IEA removed.
• wol mutant: vascular (phloem/procambium) patterning PMID:11114883.
• Downstream: sulfate transporter repression PMID:15144379 -> GO:1902358 'sulfate transmembrane transport' marked over-annotated (regulation, not transport; no 'negative regulation of sulfate transmembrane transport' term found in OLS).
• ER localization [PMID:21709172; PMID:21841169].