Figure 1.

Fluorescent PIP_n and IP_n analogs are rapidly delivered to cells by a polyamine carrier. (a) Structures of chemical probes used in this study. Left to right: fluorescent PtdIns(4,5)P₂ and PtdIns(3,4,5)P₃ analogs, fluorescent Ins(1,4,5)P₃, and two fluorescent Neo derivatives. The open arrows indicate the two primary aminomethylene (-CH₂NH₂) substituents that could be modified by the fluorophore. (b) NIH 3T3 mouse fibroblast cells with internalized PtdIns(4,5)P₂-NBD-histone complex; in the no-carrier control (Inset) the green fluorescence of PtdIns(4,5)P₂-NBD is extracellular. (c) Ins(1,4,5)P₃-XRITC was delivered to NIH 3T3 cells by using histone as carrier; (Inset) the no-carrier control. (d) PtdIns(3,4,5)P₃-NBD was delivered into NIH 3T3 mouse fibroblasts by using histone as carrier; (Inset) a higher-magnification image. Images were collected 30 min after fluorescent probe addition for no-carrier controls (b Inset and c Inset) and 5 min (b) or 10 min (c and d) after the complexes were added to the cells. See http://www.biology.usu.edu/pipncells/. Magnifications: b and c, ×240; b and c Insets, ×100; d, ×100; and d Inset, ×360.