TIMM23 SORT inserts proteins into inner membrane

As inferred from the yeast TIM23 complex, the human TIMM23 complex resides in the inner membrane of the mitochondrion and transfers precursor proteins to the inner membrane. The presequences of proteins targeted to the inner membrane are transferred to the matrix where they are cleaved. Sequences in the mature regions of the proteins then interact with the TIMM23 complex to halt transfer across the inner membrane and the proteins are released laterally into the inner membrane. TIMM21 is required.<br>In yeast experimentally verified substrates of the TIM23 complex targeted to the inner membrane include CYB2, DLD (LDHD in human), ATP9 (ATP5G1 in human), COQ2, TIM54 (TIMM54 in human), COX4, COX5A, and ATP2 (ATP5B in human). Many other inner membrane proteins are believed to be substrates of the TIMM23 complex.

依据对酵母TIM23复合体的推断，人类TIMM23复合体位于线粒体内膜，并负责将前体蛋白转运至内膜。靶向内膜的蛋白前导序列被转移至基质中，在那里被切割。随后，蛋白成熟区域的序列与TIMM23复合体相互作用，以阻止蛋白跨内膜的转运，并最终使蛋白横向释放至内膜。TIMM21的参与是必需的。<br>在酵母中，经实验验证的TIM23复合体靶向内膜的底物包括CYB2、DLD（人类中的LDHD）、ATP9（人类中的ATP5G1）、COQ2、TIM54（人类中的TIMM54）、COX4、COX5A以及ATP2（人类中的ATP5B）。许多其他内质膜蛋白被认为也是TIMM23复合体的底物。