Ca2+-independent Binding of Anionic Phospholipids by Phospholipase C δ1 EF-hand Domain

Abstract

Background:The conserved EF-hand (EF) domain is necessary for active phospholipase. Results: EF binds to anionic phospholipid-containing vesicles; EF mutations introduced into PLC ␦1 reduce activity not recoverable with added PIP 2 . Conclusion: EF-hand domain aids substrate binding in the active site when the protein is membrane-anchored. Significance: This may be the function of the EF-hand domain in other PLC enzymes as well.

Phospholipase C and D regulation of Src, calcium release and membrane fusion during Xenopus laevis development

“…The saturation and presence of a single double bond in PI decreased during fertilization and this may relate to the fact that PLC prefers 18:0 at the sn-1 position of PI45P2. Alternatively, with low Ca +2 , PA may bind to the EF hand domain of PLC to activate and change substrate specificity through a 15-fold increase in the hydrolysis of PI (Cai et al, 2013). In similar work, growth factor elevation of PI45P2 and phosphatidylinositol 3,4,5-trisphosphate (PI345P3) levels is dependent upon the translocation of Nir2 to the plasma membrane, and PA production is believed to be crucial since PA, but not PS or PI, can bind and translocate Nir2 (Kim et al, 2013).…”

Phospholipid-binding Sites of Phosphatase and Tensin Homolog (PTEN)

“…As discussed previously (18,19), if the protein contains a single spin label and the ligand binds to a discrete site on the protein, the average distance r PϪe between a bound phospholipid phosphorus and the unpaired electron of the spin-labeled proteins can be extracted from both R P-e (0) and P-e along with the concentration of the protein and phospholipid, [ When more than one cysteine bears a spin label, as is the case for PTEN, the relaxation will be the sum of paramagnetic relaxation enhancement from the different label positions, and the distance calculated, r app , reflects contributions from multiple spin labels. However, because R P-e (0) depends on r P-e Ϫ6 , only very close spin labels will have a strong effect on the 31 P relaxation of the ligand (20,21). Because r app 6 is what is extracted, we will primarily use this parameter for comparisons with different samples.…”

d -3-Deoxy-dioctanoylphosphatidylinositol induces cytotoxicity in human MCF-7 breast cancer cells via a mechanism that involves downregulation of the D-type cyclin-retinoblastoma pathway

“…1. This methodology has been applied to phospholipids in vesicles binding to discrete sites on spin-labeled proteins [20, 21] and to different short-chain phospholipids in micelles binding to spin-labeled PTEN [22]. …”

“…When the field dependence R 1 profile for the 31 P in the molecule of interest is measured using a spin-labeled protein and then compared to that for an unlabeled protein (at the same concentration), the specific relaxation enhancement due to proximity to the spin-label, ΔR 1 = R 1 (spin-labeled protein) – R 1 (unlabeled protein), can be obtained [17, 20, 21]. To quantify this paramagnetic relaxation enhancement of R 1 , or PR 1 E, the field dependence profile of this difference in R 1 at each field is fit to the following expression: …”