The structural characteristics of human preprotein translocase of the inner mitochondrial membrane Tim23: Implications for its physiological activities

► Tim23 is the core of TIM23 complex. ► We determined its structural characteristics, assembly behaviors and pH-dependent conformational changes. ► The non-bound hydrophilic domain of the human Tim23 is in a molten globule configuration with marginal stability. ► Tim23 exists as a dimer. ► Tim23 forms a compact structure at pH 4 and 3.