The Chirality of Phosphatidylserine and the Activation of Protein Kinase C

Publisher Website
Google Scholar
Abstract
The properties of phosphatidyl-l-serine (l-PS) and phosphatidyl-d-serine (d-PS) were compared. The two forms of PS have similar but nonidentical l to l phase transition temperatures. Mixtures of phosphatidylserine with phosphatidylethanolamine and cholesterol (molar ratio 1:1:2) show polymorphic behavior at higher temperatures and in the presence of Ca2+. Mixtures with l-PS undergo conversion to nonlamellar phases at lower temperatures than do similar mixtures with d-PS. The aggregation of vesicles upon addition of histones is greater for l-PS than for d-PS. With fluorescence digital imaging microscopy we could show differences in the extent of formation of histone-induced domains enriched in PS or in diacylglycerol. The most enriched domains were induced with histone in membranes containing l-PS. The MARCKS peptide showed no differences in domain formation between l-PS and d-PS. The maximal activity of protein kinase C was greater in the presence of l-PS when histone, which could form more enriched domains, was the substrate. However, with a MARCKS peptide substrate, which formed domains of equal enrichment with l-PS and d-PS, the maximal activity of protein kinase C was the same with d-PS and with l-PS. These observations demonstrate that l-PS and d-PS have different physical properties. These differences likely contribute to the greater ability of l-PS to activate protein kinase C.