forkhead associated (FHA) domain found in chloroplastic zeaxanthin epoxidase (ZEP) and similar proteins
ZEP, also called protein ABA DEFICIENT 1, ABA1, protein IMPAIRED IN BABA-INDUCED STERILITY 3, protein LOW EXPRESSION OF OSMOTIC STRESS-RESPONSIVE GENES 6, or protein NON-PHOTOCHEMICAL QUENCHING 2, plays an important role in the xanthophyll cycle and abscisic acid (ABA) biosynthesis. It converts zeaxanthin into antheraxanthin and subsequently violaxanthin. ZEP is required for resistance to osmotic and drought stresses, ABA-dependent stomatal closure, seed development and dormancy, modulation of defense gene expression, and disease resistance and non-photochemical quencing (NPQ). The FHA domain is a small phosphopeptide recognition module.
Feature 1:putative phosphopeptide binding site [polypeptide binding site]
Evidence:
Comment:based on structures of other FHA domains with bound phosphopeptide
Comment:GR at the C terminus of strand beta3, SRxH just preceding beta5, and motif SxNG in the beta6-beta7 turn indicate a canonical mode of pThr recognition.
Comment:Conserved residues are involved in binding directly to the ligand backbone and phosphate group. Non-conserved residues may determine binding specificity.
Jiyao W et al.(2023). "The conserved domain database in 2023.",