C-terminal tubby domain of the Mus musculus tubby bipartite transcription factor (Tub) gene (MGI:2651573), mutated to carry a R332H amino acid substitution. Tag:mTb(R332H) binds specifically to phosphatidylinositol 4,5-bisphosphate, with negligible affinity for inositol 1,4,5-trisphosphate (PMID:18420701). It can thus be used to monitor the distribution of phosphatidylinositol 4,5-bisphosphate within a cell, if fused to an appropriate reporter protein, or to target a tagged protein to a particular subcellular localization via phosphatidylinositol 4,5-bisphosphate binding. For a review of the properties of Tag:mTb(R332H) and a comparison with other genetically encoded lipid biosensors, see PMID:29953345.