(Get4)2(Get5)2 tetrameric complex is stabilized via Get4/4 interface. (A) Structural representation highlighting a putative homodimeric interface in Get4 (PDB: 2WPV), formed by intersubunit hydrogen bonds, and hydrophobic and ionic interactions. (B) Mass spectrum of the Get4-Get5∗ heterotetramer. Like before, we observe a population of Get4 without the first two residues. This population is present in all the complexes containing Get4, as shown in the inset. (C) MS/MS spectra of (Get4)2(Get5∗)2. CID MS/MS of the (Get4)2(Get5∗)2 produced led to the loss of monomeric Get5 (left panel), leaving behind the remainder of the trimeric (Get4)2Get5 (right panel). Similar spectra were obtained for two independent protein preparations. To see this figure in color, go online.