Abstract
The correct delivery of noncytoplasmic proteins to locations both within and outside the cell depends on the appropriate targeting signals. Protein translocation across the bacterial plasma membrane and the eukaryal endoplasmic reticulum membrane relies on cleavable N-terminal signal peptides. Although the signal peptides of secreted proteins in Bacteria and Eukarya have been extensively studied at the sequence, structure, and functional levels, little is known of the nature of archaeal signal peptides. In this report, genome-based analysis was performed in an attempt to define the amino acid composition, length, and cleavage sites of various signal peptide classes in a wide range of archaeal species. The results serve to present a picture of the archaeal signal peptide, revealing the incorporation of bacterial, eukaryal, and archaeal traits.