TMB-Hunt: a web server to screen sequence sets for transmembrane β-barrel proteins. TMB-Hunt is a program that uses a modified k-nearest neighbour (k-NN) algorithm to classify protein sequences as transmembrane β-barrel (TMB) or non-TMB on the basis of whole sequence amino acid composition. By including differentially weighted amino acids, evolutionary information and by calibrating the scoring, a discrimination accuracy of 92.5% was achieved, as tested using a rigorous cross-validation procedure. The TMB-Hunt web server, available at, allows screening of up to 10 000 sequences in a single query and provides results and key statistics in a simple colour coded format.