Venn diagrams of proteins identified from 2D gels derived from three different membrane fractions (A) and proteins with more than one transmembrane domain (TMD) identified in 2D gel vs . 2D-LC-MS/MS experiments (B). Acronyms are described in the flowchart of Figure 1. 2D gel-based protein identifications included several Y. pestis growth conditions, while those identified from 2D-LC-MS/MS efforts were limited to stationary phase cell growth at 26°C. The analysis of TMDs is based on bioinformatic motif predictions by the algorithm TMHMM.