We have developed a novel approach for dissecting transmembrane beta-barrel 
proteins (TMBs) in genomic sequences. The features include (i) the 
identification of TMBs using the preference of residue pairs in globular, 
transmembrane helical (TMH) and TMBs, (ii) elimination of globular/TMH proteins 
that show sequence identity of more than 70% for the coverage of 80% residues 
with known structures, (iii) elimination of globular/TMH proteins that have 
sequence identity of more than 60% with known sequences in SWISS-PROT, and (iv) 
exclusion of TMH proteins using SOSUI, a prediction system for TMH proteins. Our 
approach picked up 7% TMBs in all the considered genomes. The comparison between 
the identified TMBs in E. coli genome and available experimental data 
demonstrated that the new approach could correctly identify all the 11 known 
TMBs, whose crystal structures are available. Further, it revealed the presence 
of 19 TMBs, homology with known structures, 60 TMBs similar to well annotated 
sequences, and 54 TMBs that have high sequence similarity with Escherichia coli 
beta-barrel proteins deposited in Transport Classification Database (TCDB). 
Interestingly, the present approach identified TMBs from all 15 families in 
TCDB. In human genome, the occurrence of TMBs varies from 0 to 3% in different 
chromosomes. We suggest that our approach could lead to a step forward in the 
advancement of structural and functional genomics.