Protoplanetary nebulae are considered to be the evolutionary link between asymptotic giant branch stars and planetary nebulae. They possess many of the physical characteristics expected of such a link and provide valuable information about the evolutionary process in these objects. One important characteristic of protoplanetary nebulae is the prevalence of very strong bipolar and point-symmetric morphologies. In planetary nebulae, these shapes are widely considered to be the result of shaping by a binary companion. Indeed a number of studies have shown links between strong axial or point symmetry in planetary nebulae and close binary central star systems that have gone through a common envelope phase. Here, we explore whether the observed protoplanetary nebulae may be the progenitors of planetary nebulae with close binary central stars. We find that despite the strong shaping of protoplanetary nebulae this is unlikely to be the case. We also discuss options for evolution to close binaries and the alternatives.