Lateral Organization of Host Heterogeneous Raft-like Membranes Altered by the Myristoyl Modification of Tyrosine Kinase c-Src.

Abstract

Membrane-bound c-Src non-receptor tyrosine kinase, unlike other acyl-modified lipid-anchored proteins, anchors to the membrane by a myristoyl chain along with a polybasic residue stretch, which is shorter in chain length than its host membrane. The packing defect arising from this mismatched chain length of the host and the lipid anchor significantly affects the lateral organization of heterogeneous membranes. We reveal the mixing of phase domains and formation of novel nanoscale-clusters upon membrane binding of the Myr-Src (2-9) peptide. Fluorescence cross correlation spectroscopy was used to explore the nature of these clusters. We show that Myr-Src (2-9) is able to oligomerize, and the peptide clusters are embedded in a lipid platform generated by lipid sorting. Further, using confocal fluorescence microscopy and FRET assays we show that localized charge enrichment and membrane curvature are able to shift the partition coefficient towards the more ordered lipid phase.