Figure 3. The archaeal cell envelope.
(A) Examples of cell envelope structures of different archaea, including: the S-layer proteins of Sulfolobus; the S-layer protein of Haloferax containing a lipid-anchor; the cell envelope of Methanothermus containing both a pseudopeptidoglycan layer surmounted by an S-layer; the cell envelope of Methanosarcina containing an S-layer and a methanochondoitin layer on top. (B) Different archaeal surface appendages: the archaellum, type IV pili, threads, fimbriae, cannulae, and hami. (C) Different N-glycan structures found especially on the surface proteins of S. acidocaldarius, S. solfataricus, S. tokodaii, H. volcanii and M. thermolithotrophicus.
