Mycobacterial phage D29 holin of 141 aas, Gp11.  Gp11 shows a lipid concentration-dependent conformational switch from an α-helix to a β-sheet structure (Lella and Mahalakshmi 2013). Toxicity has been studied showing that TMS 1 (but not TMS 2) and a C-terminal coiled-coil region are essential for activity because the latter is necessary for holin aggregation, insertion into the membrane and bacterial cell death (Kamilla and Jain 2015).  A role for TMS 2 in pore formation has been proposed (Lella and Mahalakshmi 2016).  The first TMS has been engineered to form a nanopore (Lella and Mahalakshmi 2016).  The D29 and Chy1 phage holins are identical in amino acid sequence (Gan et al. 2016).