In budding yeast, Get4 is part of the GET complex that inserts the tail-anchored (TA) proteins into the endoplasmic reticulum membrane [1,2]. In humans, Get4 is part the BAG6/BAT3 complex, maintains misfolded and hydrophobic patches-containing proteins in a soluble state and facilitates their proper delivery to the endoplasmic reticulum, or alternatively promotes their sorting to the proteasome where they undergo degradation [3,4,5,6]. The BAG6/BAT3 complex is involved in the post-translational delivery of tail-anchored/type II transmembrane proteins to the endoplasmic reticulum membrane [3,6,7].

1: Interaction surface and topology of Get3-Get4-Get5 protein complex, involved in targeting tail-anchored proteins to endoplasmic reticulum. Chang YW, Lin TW, Li YC, Huang YS, Sun YJ, Hsiao CD; J Biol Chem. 2012;287:4783-4789. PMID:22190685

2: Crystal structure of ATP-bound Get3-Get4-Get5 complex reveals regulation of Get3 by Get4. Gristick HB, Rao M, Chartron JW, Rome ME, Shan SO, Clemons WM Jr; Nat Struct Mol Biol. 2014;21:437-442. PMID:24727835

3: A ribosome-associating factor chaperones tail-anchored membrane proteins. Mariappan M, Li X, Stefanovic S, Sharma A, Mateja A, Keenan RJ, Hegde RS; Nature. 2010;466:1120-1124. PMID:20676083

4: A ubiquitin ligase-associated chaperone holdase maintains polypeptides in soluble states for proteasome degradation. Wang Q, Liu Y, Soetandyo N, Baek K, Hegde R, Ye Y; Mol Cell. 2011;42:758-770. PMID:21636303

5: Protein targeting and degradation are coupled for elimination of mislocalized proteins. Hessa T, Sharma A, Mariappan M, Eshleman HD, Gutierrez E, Hegde RS; Nature. 2011;475:394-397. PMID:21743475

6: Mechanistic basis for a molecular triage reaction. Shao S, Rodrigo-Brenni MC, Kivlen MH, Hegde RS; Science. 2017;355:298-302. PMID:28104892

7: Bag6 complex contains a minimal tail-anchor-targeting module and a mock BAG domain. Mock JY, Chartron JW, Zaslaver M, Xu Y, Ye Y, Clemons WM Jr; Proc Natl Acad Sci U S A. 2015;112:106-111. PMID:25535373