Fig. 2
Classification of the human PX domains based on their phosphoinositide-binding preferences. a The relative binding of each PX domain to phosphoinositide membranes was estimated based on the Coomassie-stained band intensities in Fig. 1. The enrichment or binding strength is defined as the ratio of the band intensity observed in the pellet (P) compared to the supernatant (S) fractions (P/S ratio). PX proteins that we could not purify (i.e., no data) are shown in white. b We have classified the PX domains into four groups. Group I proteins do not bind to any lipids under the conditions tested. Group II includes those that specifically bind to PtdIns3P. Group III members bind to PIP2 (PtdIns(3,4)P2/PtdIns(3,5)P2/PtdIns(4,5)P2) and/or PIP3 (PtdIns(3,4,5)P3) and/or PS, but not PtdIns3P. Group IV includes the PX proteins that bind to both PtdIns3P and PIP2/PIP3/PS. c Phylogenetic analysis of the human PX domains performed with Phyology.fr50, using sequence alignments guided by secondary structure predictions defined by PRALINE51. Proteins are color-coded based on their phosphoinositide-binding grouping, and those with known X-ray crystal or NMR structures are indicated
