Required for dimerization of active 70S ribosomes into 100S ribosomes in stationary phase; 100S ribosomes are translationally inactive and sometimes present during exponential growth. Able to dimerize E.coli 70S ribosomes in vitro (PubMed:24279750). Interacts with 100S ribosomes in stationary phase; alters the relative position of the 30S and 50S subunits. The N-terminus (residues 1-126) is homologous to YaiA and HPF of E.coli and can associate with ribosomes, while the C-terminus (residues 126-185) seems to be a functional paralog of E.coli RMF. No visible effect on growth until cells have been starved for 5 days; cells recover from starvation less well than wild-type and are dead after 14 days starvation. No 100S ribosomes are formed even in stationary phase. Belongs to the HPF/YfiA ribosome-associated protein family. Long HPF subfamily.