2.A.105.1.1
Mitochondrial pyruvate carrier, MPC1/2/3 (MPC1: 130 aas and probably 3 TMSs; MPC2: 129 aas and 3 TMSs; MPC3: 146 aas and 3 TMSs) (Bricker et al., 2012; Herzig et al., 2012). Yeast MPC proteins with 3 TMSs and a matrix-exposed N-terminus are imported by the carrier pathway, using the receptor Tom70, small TIM chaperones, and the TIM22 complex (Rampelt et al. 2020). The TIM9.10 complex chaperones MPC proteins through the mitochondrial intermembrane space using conserved hydrophobic motifs that are also required for the interaction with canonical carrier proteins. Thus, the carrier pathway can import paired and non-paired TMSs and translocate N-termini to either side of the mitochondrial inner membrane, revealing an unexpected versatility of the mitochondrial import pathway for non-cleavable inner membrane proteins (Rampelt et al. 2020). MPC transporters have been reviewed (Cunningham and Rutter 2020).