Abstract: Disclosed herein are methods and compositions related to engineered fragments of the human transglutaminase-related protein family, described herein as engineered transglutaminase barrel proteins (ETBPs), that have utility as high affinity, high selectivity target-binding proteins offering advantages as antibody equivalents for therapeutic, analytical, manufacturing and research purposes. ETBPs differ from naturally occurring human transglutaminase fragments by the addition, deletion, replacement and/or substitution of the naturally occurring amino acid sequence. ETBPs can be easily expressed in prokaryotic cells and in many cases can be purified by a simple solubilization and precipitation method.