P4M domain of the Legionella pneumophila sidM gene (GB:DQ845395). This domain binds specifically to phosphatidylinositol 4-phosphate. This domain can thus be used to monitor the distribution of phosphatidylinositol 4-phosphate within a cell, if fused to an appropriate reporter protein, or to target a tagged protein to a particular subcellular localization via phosphatidylinositol 4-phosphate binding (PMID:24711504). For a review of the properties of Tag:P4M(sidM) and a comparison with other genetically encoded lipid biosensors, see PMID:29953345.