Predicted secondary structure of the 20 S proteasome and model structure of the putative peptide channel.

Secondary structure prediction has made great progress in recent years due to the incorporation of evolutionary information, and may be close to a point where (in combination with biochemical and low-resolution structural data) it can guide the modelling of tertiary structure in cases where no model building is possible by homology. Towards this goal it is important to gather information on the performance of prediction methods in advance of the publication of new structures. In anticipation of the soon-to-be-released structure of the 20 S proteasome from Thermoplasma acidophilum, we have applied several widely used secondary structure prediction methods to proteasome sequences and have attempted to model the putative channel in the outer proteasome rings (alpha-rings) based on the obtained predictions.