Self-Assembly of Qβ and MS2 Phage Particles: Possible Function of Initiation Complexes

Abstract
Four kinds of particles were reconstituted with RNA and protein from the genetically unrelated bacteriophages Qβ and MS2, namely, two homologous and two heterologous, with respect to RNA and protein. However, once Qβ RNA (or MS2 RNA) reacted with a few molecules of either Qβ or MS2 protein to form a nucleoprotein complex (initiation complex), it formed a phagelike particle only with subsequent addition of the same protein.