The Lin domain is required for correct localization of AtPIP5K5, NtPIP5K6-1, and AtPIP5K2. The PI4P 5-kinases AtPIP5K5, NtPIP5K6-1, and AtPIP5K2 belong to subfamily B and share the same domain structure. N-terminal domains of AtPIP5K5, NtPIP5K6-1, and AtPIP5K2 were systematically deleted, the truncated variants fused to EYFP-tags, the fusion proteins expressed in tobacco pollen tubes, and the fluorescence distribution was monitored. (A) Graphical representation of the domain structure of full-length AtPIP5K5, NtPIP5K6-1, or AtPIP5K2. NT, N-terminal domain; MORN, MORN domain; Lin, linker domain; Dim, dimerization domain; Cat, catalytic domain; AL, activation loop; EYFP, fluorescence-tag. ΔNT–MORN, graphical representation of the ΔNT–MORN truncations; ΔNT–MORN–Lin, graphical representation of the ΔNT–MORN–Lin truncations. (B–D) Subcellular distribution of AtPIP5K5 (B), AtPIP5K5ΔNT–MORN (C), and AtPIP5K5ΔNT–MORN–Lin (D). (E–G) Subcellular distribution of NtPIP5K6-1 (E), NtPIP5K6-1ΔNT–MORN (F), and NtPIP5K6-1ΔNT–MORN–Lin (G). (H–J) Subcellular distribution of AtPIP5K2 (H), AtPIP5K2ΔNT–MORN (I), and AtPIP5K2ΔNT–MORN–Lin (J). Images are representative for ≥300 transgenic pollen tubes observed. Bars, 10 μm.