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. Author manuscript; available in PMC: 2013 Sep 3.
Published in final edited form as: Nat Rev Mol Cell Biol. 2011 Nov 16;12(12):787–798. doi: 10.1038/nrm3226

Figure 4. TA protein sorting by the TRC.

Figure 4

The TMD recognition complex (TRC) consists of a stable core complex (depicted in grey) and several dynamically associated components. In budding yeast, the TRC core consists of Get4 and Get5, with Get4 recruiting Get3, and Get5 recruiting Sgt2. Sgt2 can additionally recruit other chaperones. In mammals, TRC35 (which is homologous to Get4) and Ubl4A (which is homologous to Get5) are in a complex with Bag6, which probably recruits SGTA (which is homologous to Sgt2). Engagement of the TRC by a substrate (probably bound to Sgt2/SGTA) results in its sorting among any of several potential TMD-binding proteins (dashed arrows). This sorting is presumably dictated by a combination of substrate features and availability of the binding partners. The substrate can therefore emerge from the TRC bound to any of multiple binding partners, each of which imparts a specific downstream fate. Get3/TRC40 association mediates ER targeting, whereas Bag6 binding can recruit an E3 ubiquitin ligase that mediates substrate degradation. The fate of other complexes are not understood but could include targeting to other destinations including the mitochondria.