Tim17

Tim17 is a small, conserved mitochondrial inner membrane protein that serves as a core component of the translocase of the inner mitochondrial membrane 23 (TIM23) complex. In yeast, the gene is TIM17, while vertebrates typically express paralogs TIMM17A and TIMM17B. Tim17 is embedded in the inner mitochondrial membrane and contributes to the formation and function of the TIM23 channel together with Tim23 and Tim50, enabling the import of most nucleus-encoded proteins destined for the mitochondrial matrix or inner membrane that carry N-terminal presequences.

The TIM23 complex relies on the mitochondrial import motor to drive translocation into the matrix, where proteins are folded by chaperones. Tim17 is thought to participate in substrate recognition and channel gating, helping maintain proper conductance and selectivity of the translocation pore. Structurally, Tim17 is predicted to be a multi-pass inner membrane protein with several transmembrane helices, and its topology positions ends in the matrix and/or intermembrane space in a way that supports complex assembly and function.

TIMM17 genes are nuclear-encoded and their products are imported post-translationally into mitochondria before becoming part of the TIM23 complex in the inner membrane. The Tim17 subunit is conserved across eukaryotes, reflecting its essential role in mitochondrial protein import and organellar biogenesis. Related components in the same pathway include Tim23, Tim50, Tim21, and the mitochondrial import motor elements such as Tim44 and mtHsp70.