Do prokaryotes have post-translational modification? - (Dec/02/2011 )

Hi, I am getting confused now. Are there post-translational modifications in prokaryotes?

If not, what are the "signal peptides" for in prokaryotes? Just for secretion?

there are post-translational modifications in prokaryotes including a large number of chemical modifications, signal peptide cleavages, and cleavages of N-terminal methionine residues.

I'm sure there are even a lot more that we havn't recognized yet!

Regards,
p