To investigate whether GltB possess more function, Co-immunoprecipitation coupled with Mass Spectrometry (CoIP-MS) was used to isolate the putative GltB binding proteins.We used strains PAO1/p-gtrS-YFP and ΔgltB/p-gtrS-YFP to ensure the membrane protein GtrS of great interest is at high levels. A target GltB-specific antibody anti-GltB was used and ΔgltB/p-gtrS-YFP was set up as a negative control. The whole gel lane was divided into small fractions and in-gel digested for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Control sample was also analyzed in parallel to distinguish the background proteins.