Signal peptide protein conformation role

The experiments described in Sections VI,A,B show that two physical properties of the synthetic LamB signal peptides correlate with their in vivo export function tendency to adopt an a-helical conformation in hydrophobic environments, and tendency to insert into lipid mono-layers. These properties may be involved in the same step in the secretion process, or in different steps. An a-helical conformation may be required to generate a structure sufficiently hydrophobic to allow mono-layer insertion. Alternatively, these properties may reflect separate roles of the signal sequence in protein secretion. For instance, an a-helical conformation may be necessary for binding to a proteinaceous site, while the ability to interact with lipids may be important for another step in the secretion process. We have studied the conformations of the synthetic LamB signal peptides in phospholipid vesicles and monolayers by CD and IR spectroscopy. 

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