Bioengineering of human thyrotropin superactive analogs by site-directed "lysine-scanning" mutagenesis. Cooperative effects between peripheral loops.

摘要: We have previously engineered the first superactive analogs of human thyrotropin (hTSH) by using a novel design strategy. In this study, we applied homology comparisons focusing on αL3 loop common α-subunit glycoprotein hormones. Seven highly variable amino acid residues were identified, and charge-scanning mutagenesis revealed three unrecognized modification permissive domains four gain-of-function lysine substitutions. Such mutations hormone- receptor-specific dependent location basic charge. Cooperativity individual substitutions was established in double triple mutants. combinations most potent analog with two characterized analogs, higher degree cooperativity for compared both αL1 hTSH-βL3 observed. demonstrated that spatially distinct regions contribute differentially to interaction hTSH its receptor modified loops same opposite sides molecule display similar increases vitro biopotency. addition, combination all showed binding activation resulting described date.