Research update
The Brix domain protein family – a key to the ribosomal biogenesis pathway?

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Abstract

Six (one archaean and five eukaryotic) protein families have similar domain architecture that includes a central globular brix domain, and optional N- and obligatory C-terminal segments, both with charged low-complexity regions. Biological data for some proteins in this superfamily suggest a role in ribosome biogenesis and rRNA binding.

Section snippets

Six families of homologous proteins with similar domain architecture 

A thorough analysis of the Brix protein sequence (339 residues) yielded several surprising findings. After applying a homologue-searching strategy in the non-redundant protein sequence database including iterative profile searches with the PSI-BLAST tool (withstandard sequence inclusion condition E<0.002 and filters for compositional bias 2) and a fan-like search heuristic (starting individual new searches with each of the significant hits), we collected a closed set of ∼50 protein sequences.

 with a suggested role in ribosomal biogenesis

More than 80% of all superfamily members (including essentially all family I, III and VI proteins) lack any functional characterization and are described solely as, for example, hypothetical proteins and conceptual translations. Several family representatives have a characterized phenotype. The protein Peter Pan (AAD16459.1) from D. melanogaster 4, T.cruzi's stage-specific protein 24 (annotation of AAD14602.1) and yeast's Ssf1/2 (Refs 8, 9, 10) are essential for general functions such as

Acknowledgements

We are grateful to E. Bogengruber, M.Breitenbach, F.M. Jantsch and G.Lepperdinger for supplying experimental data on sequence and function of Brix (AF319877) and yol077c before publication and for extensive discussion of the Brix sequence analysis results. This research was supported by Boehringer-Ingelheim International.

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