1.S.  Bacterial Micro/NanoCompartment Shell Protein Pores  Bacterial Micro- or Nano-compartments fall into a class of proteinaceous 'organelles' or machines that serve a specific metabolic function (Saier 2013). The metabolic enzymes are sorrounded by 'shell' proteins, many of which are homologous and form oligomeric structures containing substrate selective pore through which substrates/products/intermediates can pass with differering permeabilities (Park et al. 2017).