Shell component of a type 1 encapsulin nanocompartment. Assembles into proteinaceous shells 23-24 nm in diameter with 2-2.5 nm thick walls. Cargo protein DyP is targeted to the interior via its C-terminal extension; probably only 1 DyP hexamer is incorporated into each shell (By similarity). Probably involved in protection against oxidative damage (By similarity). Found in a complex with DyP, suggesting it is the native cargo protein (PubMed:25500374). Monomers form pentamers, which assemble to form hollow shells composed of 60 subunits with several openings (By similarity). Belongs to the encapsulin family. Family 1 subfamily.