FIGURE 1: Schematic surveys of potential non-lytic secretion pathways that involve holin-mediated transport in Gram-negative (A) and Gram-positive (B) bacteria. Holins (H, red) are included with two protomers to symbolize that association of multiple protomers is expected to be required for transport. Examples for substrates (S, blue) of specific pathways are mentioned. Endolysins or endolysin domains are indicated (E, green), as is the Sec translocon (Sec, brown). Lipoteichoic acids are symbolized by a dashed black line. See text for more details.